I did a little digging into this just yesterday. The impression I got was that Claude Code was pretty great, but also used a _lot_ more tokens than similar work using aider. Conversations I saw stated 5-10x more.
So yes with Claude Code you can grab the Max plan and not worry too much about usage. With Aider you'll be paying per API call, but it will cost quite a bit less than the similar work if using Claude Code in API-mode.
I concluded that – for me – Claude Code _may_ give me better results, but Aider will likely be cheaper than Claude Code in either API-mode or subscription-mode. Also I like that I really can fill up the aider context window if I want to, and I'm in control of that.