Against the Open Sicilian generally, it's hard to play the "same" system against everything.  There's a system that makes every White set up critical: even for the g3 systems (Taimanov!).  It's best not to try to play different variations in the Sicilian on the same general principles.

If you're looking to avoid theoretical criticality, however:

Sveshnikov: 9 Nd5 Be7 10 Bxf6 Bxf6 11 g3.
Najdorf/Scheveningen: 6 g3.  There's lots of theory, but you don't actually have to learn it all to survive the opening.
Taimanov: Look at lines with Nb5/Ndb5.
Dragon: Be3&Be2 lines, castle either way as suits your fancy.