95 was a huge advancement over 3.1, but it was sorta only halfway to NT, so it wasn't particularly stable as a result. Light as hell, though, for modern 32-bit Windows. 98 and 98SE were heavier by quite a bit, but also much stabler.
2000 I've been playing around with, and I'm quite impressed at how light and responsive it is, and solid as a rock; I wish this had been the OS that took off and gained popularity rather than XP, then there'd be better, newer hardware I could run it on.