I'm not going to tell you whats right or wrong on brand choices, but I will tell you, if you're seriously considering a used C5, go with at least an 01 model. They made several running changes in 01, especially with the block and motor. All 01 and later C5s, thanks to the release of the Z06 in 2001, got the LS6 block and LS6 intake. They definitely run a little stronger.
If you still want a pre-01 C5, I'd probably recommend a 99 or 00 FRC model (thats the same body as the Z06 became in 01). That car is considerably lighter than the hatchback coupe, and runs stronger. The chassis is also stronger.