Hm, you don't exactly have the option I would choose, and that's "Whatever is handy." If I have approriate miniatures (or even close proximities) I'll use those, if not, tokens, beads, coins, dice, etc...
Don't have an option that works for me (Normally nothing, but somtimes whatever we can come up with (dice, coins, etc) if a combat is really really tricky.).
cheap, plastic minis out of the First Quest boxes for PCs, and a combo of Creature Collection 1 & 2 from FDP and DragonScale counters for NPCs and monsters.
We're looking to upgrade to metal minis. One of the guys in the group is offering to paint, as I lack the time, talent, and money to get into that.