I'm a big fan of starting somewhere solid.
Subaru - GRIP and tons of aftermarket
Evo - Same
S2K - Handling game is great
newer muscle cars - HP game is there with very little mods
etc.
For me that has always been a Mustang or old muscle car, but mainly mustang. It doesn't handle, but it has decent power, plus there is a TON of potential there.
Some careful suspension mods, and a little power increase, the thing is fun.
If I'm not racing a car on the track, it is more about just having fun than all around performance. Plus I love the symphony of 8-cylinders.
Honestly though, I think you'd do well with an older WRX. Yes, they are 5-spd, but I did a run in one back in my Auto-X days several years ago and he had only a few mods. Upgraded brake pads, exhaust, tire upgrade and shocks, the thing gripped amazingly well. Plus it had good power with the stock turbo powerplant. Not the fastest thing out there, but it was super fun and he even admitted it was crazy fun to drive every day. It was exactly that day I became a Subaru fan.