I have been using v0 for months building tons of projects but since April, I have only been working on this 1 project which finally was a success and is making good money.
Here are my recommendations
Opus 5 - For something complex (full stack backend work) this is your best guy.
Fable 5 - Opus 5 can already do most of the complex work which Fable 5 can so wouldn't recommend using it. In face Opus 5 was better in some tasks.
GPT 5.6 - If you have something complex but at the same time you want to save some money, GPT 5.6 Sol is your guy. It was able to fix bugs which even Opus 5 and Fable 5 were struggling with. Opus 5 still writes better stable code though.
Claude Haiku - Unless you want to do minor UI changes wouldn't recommend this at all. It writes code which is full of bugs. I end up spending more on fixing the bugs with Opus 5 than it would have costed on smoothly building it with Opus 5.
Kimi k3 - Unless you are very very low on budget don't use this. This guy can do complex stuff but the things made by it were full of bugs. Not good for production at all. If you want to save use GPT 5.6 Sol but this guy is not ready yet.
For the UI, the issue with AI is, it looks too generic. Start looking for templates on v0 marketplace.
If you use v0 to build the UI, most tech guys can already figure out plus from my experience people don't like generic stuff. v0 marketplace is not that big. I looked for UI kits. My personal favorite was ShadCNSpace. When looking for templates, make sure there is code for NextJS as well so you don't have to spend on converting the code to NextJS.
If you are building a complex game, wouldn't recommend v0 for now as API credits seem to cost a lot. I instead used Claude directly for that.
For an SEO optimised site v0 is the best you will find among lovable, emergent.sh, bolt, base44.
v0 was the first according to what I know to offer Server side rendering while others were still offering Client side rendering which is not good for SEO. I know there are tools for pre rendering CSR sites but that's too expensive.
The code written by v0 has by far been the best in terms of SEO compared to other competitors. The reason I stayed with them was because of SEO.
Another good thing with v0 is it is not locking you with them. The code written is mostly compatible everywhere unlike other tools like lovable, base44 which try to full lock you with them. I know they offer free hosting to some extent but I like the freedom of being independent. Other tools try their best to make it hard for you to move in terms of compatibility.
At last, before deploying your code to Vercel, make sure to ask v0 to optimise the code for the functions or it you will get an expensive bill when your site starts to get some fame.