240SX + SR swap is a big project, RB swap is a bigger project. I would shy away from the RB personally. Plus lately 240 owners have become a bunch of fucktard wannabe drifter stunnas, it's really bad. Of course you should buy the car for the car and not the people who drive it, but still...

300ZX TT and Supra TT are both heavy, but if you like the sort of high powered fat-cat rwd GT/cruiser thing they're both nice. The Supra will get you revved at by every damn thing, the Z is a bit more stealthy because it doesn't have as much of a reputation. The Supra is a newer design by 3 years, so the Z has a bit of late-80's flava to it (not a bad thing necessarily) while the Supra feels thoroughly up-to-date.

The WRX really underwhelmed me when I took one for a drive. The stock tires and suspension are ehh, but if you plan on fixing both of those issues right away I guess it could be a fun car.