My personal favorites are;
Aquarius / Vision Technologies MB-4DUVC and MB-4DUPM. The DUVC is a VLB board with the UMC 8498 chipset, the 4DUPM is a PCI/VLB board with the UMC 8886 chipset. Older VLB boards don't usually have onboard I/O, the PCI ones I am listing all have onboard IDE/COM etc.
There are boards out there such as the JK-042A (No idea who made it, Wan Hung Lo I guess) which are basically the same as the 4DUV and if you avoid the PCChips ones with fake cache, these are usually good. In fact, if you can get one with 3.45V support, they can run an AMD X5 and keep up with a PCI system pretty nicely. Possibly even beat a PCI board at higher BUS clocks. Seems most of them also run the Pentium OverDrive just fine as well.
Most people swear by the Bioteq MB-8433UUD. I don't like it personally, but there's nothing wrong with it. Essentially the same (in function) as the 4DUPM but without VLB slots, you wouldn't need them as the 8881/8886 has a real PCI implementation instead of a cheap bridge.
MSI MS-4144, a reasonably fast PCI board based on the SiS 496 chipset. Doesn't have the best CPU support, but it does run DX4WB chips from AMD at least and the PCI implementation is actually pretty good.
DTK PKM 0038s - I think this is an older VLB board, but pretty good for an SX, DX or even a DX2 system. I ran one briefly years ago and it was solid... Actually, I kinda miss it and they do come up from time to time, but I guess I like my DUV better.
Believe it or not, the PCChips M919 is meant to be OK, just be weary of the cache module as they are proprietary and expensive, you would probably never find one. Never used this board myself so this one isn't from my personal recommendations. I will have to get one eventually though because I am reverse-engineering the cache module so copies can be made cheaper, they are not very complicated.