Different cores: Apollo. Note both ATI and NV cards. They're crap, though.
BFG: Nope, so I noted that was what I was consistently seeing from people who've had a good bit more crads through their hands than me, rather than 1st-hand experience.
Most ATI cards are made by the manufacturer, but using the ATI reference design. This helps a bit, but there will still be differences. Basically the same as NVidia, but they put their name on some Sapphire made cards, and sometimes, on taking the heatsink and such off, they have been shown to have different RAM, caps, etc., so you don't really know if it matches what ATI would sell under their name.
...OTOH, DVI-D is here to stay, and except for the real low-end, you won't your eyes much with any of them.
Cards, then...
STB Voodoo2 12MB. Poor 3Dfx. Oh, through a S3 Virge.
ELSA (made by visiontek) GF2. Still in use by a friend. New fan scotch-taped to it. Modded it for better 2d, even though it wasn't shabby at the time.
Rage128 AIW: OK all-around, not bad now that the drivers work. Took way too long for that, though.
Abit GF4 Ti 4200 suffered mysterious death. Nice card, got to 300/600 stable.
Powercolor 9800SE suffered wierdness over the first few days. RMA'd.
Info-Tek 9600 XT (not as good 2d as BBA or the leadtek, but not bad). Gradually got artifacts at stock speeds, need to RMA it. Fan was starting to be noisy, but I doubt that was it, fiven the 4th one.
Leadtek 5900 XT. Very light artifacting, after just a couple weeks. Need to do some testing w/ a meter to be sure the PSU isn't doing anything funky. If it's looking fine, new mobo and RMA the card (can't RMA the mobo to the Egg anymore

).
The GF4 and up problems started with the new mobo and PSU, but couldn't pin them down until this Leadtek started it, as it's awesome and seems to have no major corners cut (aside from no RAMsinks, but no biggie there). I'm confident now that all four cards were fine before they got powered in this AGP slot. The list includes only cards I've used personally, not counting fixing PCs and building them. And aside from the minimal and fleeting artifacts, I like this Leadtek and will attempt to get another of the same model.