Personally, I prefer Shimano over SRAM. I had Shimano Deore components on my old MTB (2010 GT Avalanche 1.0 Disc) and it never skipped a beat. It shifted crisp,and was just dead reliable. I think I have SRAM X7/X9 components on my current MTB and they've hiccuped a few times.

They both have their high points and low points. I'd be more likely to reach for the bike with the Shimano group, but I don't have anything against SRAM. My "standard" are the Shimano Deore group.