Which one should I use? RCX vs NXT?

Many people have written about this subject. I think it really depends on your experience. If you have kids on your team that know a little about Robolab programming, RCX is still a very good choice. Otherwise, NXT should be used.

I have built several robots using RCX and NXT doing similar missions. The NXT robot is always a little bigger. The wires are harder to hide.

I have also used both Robolab and NXT-G programming. Robolab 2.9.4 is pretty good. One complaint I have about Robolab is the need to use container numbers. They are gone now as we can use simple variable names and formulae. In fact, formulae is better handled b Robolab programs than in NXT-G. For people new to programming, NXT-G is easier to use. For people who have been programming with Robolab, 2.9.4 does offer a lot of nice surprises.