Jorpho, old Adlib and Roland cards come to mind as having a lot of support from games pre Sound Blaster era. Old Sound Blaster ISA cards also seem to handle some of those old games easier as well. It's not necessary to have these as they're expensive most of the time. But just having an ISA slot is really helpful if you decide to go that route.

I know the whole hard drive issue isn't a major one but there are several games (Crystal Caves comes to mind) that will install effortlessly to a smaller hard drive as opposed to configuring them to run on a larger one. Just ease of use for me.