AI Coding Agents Compared: Which Harness Is Worth Your Money?

If you think the AI model is the only thing that matters in the agentic era, you're missing half the picture. After spending weeks with five different AI coding harnesses—Codex, Claude Code, MiniMax Code, Hermes Agent, and Antigravity—I'm convinced that the interface wrapping these models determines whether your experience feels like wielding a precision instrument or fighting a stubborn teenager. Here's my direct breakdown of what works, what frustrates, and which tool actually deserves your $100.

The Short Answer: Codex Wins on Quality, MiniMax Wins on Value

Codex with GPT-5.5 is the fastest, most polished coding harness I've tested. It's the app all the others have apparently tried to imitate—the interface design, the workflow, the response quality. But it costs $100 per month, and that price tag is justified only if you need that elite performance daily.

MiniMax M3 surprised me. I expected it to be terrible based on earlier versions I'd dismissed as the "hold my beer" model—capable but chaotic. M3 changed that narrative. At $100 per year (billed annually, around $8-9 monthly effective cost), it powers two Hermes agents simultaneously plus MiniMax Code itself. That's an absurd value proposition if you can tolerate occasionally writing multiple prompts where OpenAI requires just one.

Why Harnesses Matter More Than You Think

A few months ago, I was locked into OpenClaw with Anthropic models for nearly everything. Then Puerto Rico happened—OpenAI banned usage through OpenClaw, and everyone got kicked off their Anthropic subscriptions overnight. That incident crystallized something for me: subscriptions, quotas, and harness stability matter enormously. You can have the world's best model wrapped in an interface that breaks with every update or buries your usage meters in settings menus you'll never find.

The harness ecosystem has matured rapidly. Notice how Claude Code desktop now looks suspiciously like Codex? How MiniMax Code and Antigravity follow the same visual language? Codex essentially defined the gold standard for AI coding harness UI, and everyone else scrambled to match it.

Codex: The Best App, The Premium Price

Codex with GPT-5.5 running at High settings (I'd prefer Extra High for some tasks) is my current daily driver. The speed is unmatched. Accuracy is exceptional. When I built the thumbnail for this comparison, I used Codex because nothing else felt as responsive.

The usage meter lives in Settings > Usage Remaining—not in a web dashboard I could easily reference. When they switched to token-based quotas, I panicked. Would the limits be neutered into uselessness? They weren't. Even better, they gave me 20,000 bonus tokens during the transition. I've been hammering MiniMax more aggressively than ever and I'm still at 6,000 tokens used. The weekly limit is set to unlimited, which is genuinely awesome.

My recommendation: skip the $20 plan. I hit those limits constantly within OpenClaw. The $100 monthly plan is what you need if you're running agents and want frustration-free usage. The $20 tier works for casual exploration, but serious developers will outgrow it immediately.

MiniMax M3: The Value Champion That Closed the Gap

I went into MiniMax Code expecting disaster. I'd written off MiniMax 2.5 and 2.7 as capable-but-unreliable—functional chaos engines that could technically accomplish tasks but rarely in the way you'd intended. "Hold my beer" energy.

M3 is different. The harness itself feels as capable as any competitor. I've only been using it for three or four days, so my task history is sparse compared to my months-deep Codex projects, but the capability is there. The subscription is a $20 annual plan that brings the effective cost down dramatically.

The tradeoff: you'll likely need multiple prompts where Codex delivers single-prompt results. MiniMax gets much closer to correct outputs than earlier versions, but it still benefits from iterative guidance. If your workflow involves complex, multi-step refactoring or architecture decisions, factor in that additional interaction time. For simple scripts, bug fixes, or documentation? M3 handles those elegantly.

Claude Code: Ecosystem Lock-In and the Desktop App Problem

I use Claude Code from the command line, not the desktop app. Why? The desktop app hallucinated wildly on me twice. First attempt: unusable. Second attempt, months later: they fixed the visual design, it looked like Codex, I thought "finally." Two days later, hallucinations returned. I'm not investigating further.

The command-line version runs with claude --dangerously-skip-permissions because my work mirrors OpenAI's internal QA methodology—granting machine-level permissions for autonomous task completion. It works reliably.

If you're invested in the Claude ecosystem and specifically need Opus or Sonnet, you're locked into their subscription. There's no equivalent harness that delivers the same model experience. I genuinely debated never spending another dollar with Anthropic after the OpenClaw incident, but Opus 4.8 is exceptional. Model degradation issues from earlier this year seem resolved—it now feels as capable as GPT-5.5.

The hidden benefit: having both Codex and Claude lets you A/B test outputs. Each model has different quirks—specific error types they miss or specific strengths they exhibit. Cross-referencing between them catches issues neither would catch alone.

Hermes Agent: Impressive but Painfully Slow

Everyone's hyped about Hermes Agent. My experience: it's better than OpenClaw in stability—OpenClaw broke something with almost every update, while my first Hermes update in a while didn't randomly break anything. That's a low bar, but Hermes clears it.

The problem is raw speed. Comparing MiniMax Code's response times to Hermes Agent is night and day. Hermes is dramatically slower with any model—OpenAI, MiniMax, Claude, any of them. The only thing that rivals its sluggishness is Antigravity.

Quality of output? I don't think it's meaningfully better than MiniMax's agent would be. The initial setup took me about an hour just to configure the model switcher so I could see all my available models. At one point, I offloaded that frustrating setup task to Claude Code because Hermes desktop was responding so slowly—and Claude's response came back suggesting Hermes Agent was actually fixing the issue. Meta.

Verdict: worth experimenting with, especially since it doesn't break on updates. But temper expectations based on speed.

Antigravity: Powerful but Confusing Usage Structure

Finding Antigravity's usage meters is a scavenger hunt: Settings > Models. The interface shows separate quota bars for Google models versus Claude models—they drain independently. Initially, you couldn't switch between Gemini and Claude mid-task without losing your conversation context. That limitation appears to have been resolved—I successfully switched providers today when I ran out of Gemini credits, and Antigravity continued the task seamlessly.

The pro plan is incredible if you need flexibility across model families. The confusing part is not knowing whether the quota behavior changed due to a subscription tier shift or a platform update. Documentation isn't clear about what triggers which behavior.

Subscription Recommendations: Plan vs. Per-Token

I strongly recommend subscription plans over per-token payments across all platforms. Per-token anxiety leads to overthinking every prompt—second-guessing whether that follow-up question was "worth it." Plans let you work naturally, though you still need to manage context windows and session clearing to optimize memory usage.

Here's my ranking for specific needs:

What I Actually Pay For

Currently running:

• Codex at $100/month for daily high-priority tasks
• Claude subscription for Opus 4.8 access
• MiniMax M3 annual plan powering two Hermes agents plus MiniMax Code simultaneously

The combined cost is significantly less than Codex alone would be if I needed everything from one provider. Different harnesses excel at different tasks—MiniMax for value-heavy routine work, Codex for speed-critical sessions, Claude for ecosystem-specific needs.

The Bottom Line

If budget weren't a concern, Codex wins unequivocally. The interface, the speed, the single-prompt accuracy—it's the benchmark everyone else is chasing.

If you're cost-conscious but still need serious capability, MiniMax M3 is the revelation. The gap between "hold my beer" chaos and reliable output has narrowed dramatically. You will write more prompts per task, but at $100 annually, the economics are hard to argue against.

OpenClaw remains buggy—stable updates are the exception, not the rule. Hermes Agent is worth watching but currently too slow for daily use. Antigravity serves specific multi-model workflows but needs clearer usage documentation.

The AI harness landscape is evolving monthly. I'll keep testing and reporting, but for right now: Codex for quality, MiniMax for value, Claude if you're ecosystem-committed, and skip OpenClaw until they fix their update cadence.

Pricing and quotas reflect what I observed in my accounts at recording time. These tools change rapidly—verify current limits before committing financially.