My personal opinion on this?
I definitely wouldn't use an AWE64 for a 486 machine. I would put an SBPro2, SB16 or MAYBE an AWE32 in that.
For Pentium stuff, definitely SB16 or AWE32. Games (in DOS, of course) that really take advantage of AWE32 I would want to run on a Pentium.
The AWE64 belongs in a Pentium II or III machine, for me. It isn't user-friendly at all in DOS (PnP drivers, MIDI emulation is absolute crap, CQM clone instead of OPL3, etc.). As a Windows 9x card the AWE64 Gold absolutely excels. This also goes for the AWE64 Value to a slightly lesser degree.
EDIT: By your signature I guess I can assume you're building a Pentium/166 MMX machine - OK. So you could get one of those AWE64 Values, and it would work OK - but remember the following:
1. In Windows 95/98 the card will perform the same as an SB16, with added MIDI capabilities. EDIT: DOS games will work perfectly with this card as long as you run them in Windows.
2. In pure DOS, the following issues will crop up:
-Forget about using the AWE as a MIDI device in DOS. The emulation drivers work with almost nothing.
-There are Plug and Play drivers that need to be loaded to get digital sound. They use up memory.
-The FM synthesis is Creative's CQM clone that sounds harsher and shallower than a real Yamaha OPL3, as found on many SB16 cards, some AWE32 cards, and all SBPro2 cards.
So I would really recommend finding yourself a real, non-Plug-n-Play Sound Blaster 16.
World's foremost 486 enjoyer.