I couldn't choose between the S2k and the Rubicon... I love both and they are two VERY different platforms. I would make a recommendation to try to source a used Honda S2000 CR... upgraded suspension, hardtop standard, rear spoiler and aggressive front fascia. (CR stands for club racing)
As far as my own go and in no particular order:
2001 Acura Integra Type R
Pheonix Yellow and 9000 RPMs of screaming honda engineering.
Mods will be primarily suspension with minor bolt ons. This would be a weekend and track car.
2003 Mustang GT
Strong build with a blower and 11.50 or better ETs
Weekend and track car
2004 Dodge Neon SRT4
Big Turbo setup, suspension and fuel mods. DD that is running mid 12s and is also a weekend road racer.
1989ish Nissan 240sx
Fully Built Weekend and DRIFT only car.
Jeep Wrangler from the 1990s... awesome cars
this is for going the places all my other cars can't
The cars that I've spent more time planning and building ideas for is the GT, the SRT and MOSTLY the Integra.
I have a whole list of others as well. these are just the top 5.