I love the Big Muff/tube screamer combo. Ive tried different multi fx units and I find them prone to crapping out just when you need them. I run my bass, 6string and slide thru just the two pedals and they haven't let me down yet. But if you're playing anything other than blues or rock you might need different FX.
Guitars save lives!!
"When the power of love overcomes the love of power;we will know peace" J. Hendrix