Get rid of 'em both and use DOSBox. 😜

If I'm not mistaken, the BX is generally preferable.

I doubt either has much over the other regarding dos, if they are both pentium boards. I never had issues with ALi and dos. Does each let you disable L1 and L2 cache for slowdown purposes? If not then that might be a consideration as some dos games are speed-sensitive.

Otherwise you might want to choose on the basis of other criteria like number of isa slots for different sound cards, or what else you might want to do other than dos.

BX:
- Disabling Pentium L1 cache has a huge impact. but disabling L2 does not make much difference.
- Anything over a Pentium-II 400 is normally multiplier locked. But earlier pentiums are often more flexible.
- Can use the throttle.exe tool to slowdown
- Good AGP hardware.
- 133MHz FSB capable, and CPU speeds up to 1400MHz with Tualatin core.

SS7:
- Disabling the caches on a K6 gives 486 like speeds.
- The later K6 mobile CPUs have a software adjustable multiplier.
- K6 CPUs have an inferior floating point unit
- ALI5 cannot use the throttle.exe tool to slowdown.
- Poor AGP hardware.

I usually work with BX boards, but have acquired an Asus P5A because I find the K6 mobiles somewhat interesting too. I have failed to reliably emulate the 486 speed ranges with a BX. A P5A with a K6 mobile should be able to do that better.

I really think if you wanted to work with socket 7, you'd be better off with the mvp3 chipset. I'd suggest a Tyan s1590 or even an Epox MVPG3/4/5

I'd avoid via socket 7 boards due to instabilities I had in the past with a few such boards. But I think the OP is trying to choose between 2 platforms he already has available.