Well considering that both cars are TOTALLY different.

S2000 is a nice convertible two seater that would make a fun weekend car, would do great on the Auto X courses and would be just all around fun, RWD, which both are but its still nice, nice car for just cruising with the top down or if your into turning competitions. Interior/Trunk space is not much.

IS300 is a VERY nice daily driver, if you get lucky and find a 5-speed one then its even better, decently quick stock, interior is roomy, nice sized trunk, sunroof, all power, lower it and find some nice wheels and a sound system and you'd be set for a daily driver, also good car, RWD, 2JZ-GE is in the car so you could go NA-T if you wanted.

What exactly are you looking for in the cars?