It all depends on what you want to use the car for? I personally love the balance and would build up the 4A-GE or add a supercharger or turbo. The 3S-GE is a heavy motor and will throw the balance off, which may or may not be a big deal to you. I've seen 2JZs, 2UZ-FEs, F20s (ugh..), etc. I'd like to see a 2ZZ-GE build but that would be a lot of money... I suppose in the end it's up to you.