Any. Depends on:
If it's in E, I'll either use my strat copy (no locking nut) or my Ibanez RG (always in E).
If it's in Eb, I'll use the strat copy and tune it down.
If it's in D, I'll either use my Jackson RR or BC Rich (no locking nut)
If it's in anything lower, I'll use the BC Rich.
But right now, I'm doing the songs in Drop C with the strat copy because the RR is in D and the BC Rich isn't working. The wiring has fucked up so there's no sound. I can put the strat in any tuning in 10 seconds. Sounds like shit though.