Trying to think of some game titles I had back then.
Whiplash was one, the max software render was alright, but the glide version looked a lot better.
Need For Speed SE was better looking in glide, but I think the performance was worse? Can't quite recall.
Original GTA supported glide, that was an odd modification. road surface blurred out and the frame rate ran way too fast (frame rate was patched later)
Mechwarrior II Mercenaries was another, the highest texture quality was only possible through 3DFX
Shadow Warrior, I don't recall it looking different between the cards, but there may have been a boxed edition for 3DFX I never got.
Die By The Sword was about the same quality, and I recall the game looking smoother, but the software render looked better to my eye.
Unreal Tournament was about the same, though the 3DFX lighting was different as I recall
Quake and Quake II (I think Quake III supported it but by that time I had an Nvidia card) was
Diablo II looked about the same, pretty sure that was one of the last games I picked up before swapping out my Voodoo 3 3000 for a Geforce.
I recall trying to play Day of Defeat and the Voodoo 3 couldn't take it, of course it was still a mod for Half Life, probably wasn't optimized.
And there were a lot of Glide compatible titles out there.
Still have a Voodoo5 5500 PCI sitting in my dual Pentium II.