Both SiS and Intel make stable, fast chipsets. Intel is slightly in the lead w/ performance, but there are a ton of good, inexpensive boards based off of fast SiS solutions. Intel tends to overclock a bit better than SiS, though. If you want dual channel DDR cheap, the SiS655 chipset is really nice though. Both have their ups and downs, but if I had to choose one company overall, I'd have to say Intel. Both are viable solutions though.
As for Via, they're alright I guess. I've never seen a P4/Via rig though, now that I think about it, other than no name mobo/CPU combos or barebones systems at Fry's. They have one crappy reputation right now, and their chipsets don't seem to be as competitve in the P4 category as SiS and Intel. I get the impression that Via's solutions for P4 simply don't and can't compete with the two solid competitors right now.
Aside from the brand new Canterwood and all...
For Intel, go with 845PE
For SiS go with SiS655
For Via.. eh.. just don't go Via.
