IME the most versatile instrument is probably a 2 pickup, 5 string with an active/passive switch. While that might be a step or two beyond your initial thinking, I think you should consider it.
IMO any 2 pickup bass can give you a wide tonal pallet to choose from. I use Fender style Jazz and PJ 5 string basses (one of each) and I haven't yet been asked for anything I can't provide. As was mentioned earlier, the versatility is really in the player. Work on that and it really won't matter what gear you use.
