SRAM’s Attack triggers are basically their X7 shifters, re-rigged to work with Shimano gears. The idea was great when Shimano Rapidﬁre was really hard to ﬁnd for last generation groups, but it’s less necessary now.
Typically for SRAM you get a more positive/clunky push/push shift that’s easier to notice when the bike is bouncing all over the place. You also get the rotating ‘in-clamp’ gear indicator, rather than the horizontal scroller. You don’t get the extra dirty cable heave of ‘proper’ SRAM 1:1 shifting, though.
It’s also a slower and more plasticky feeling shift than XT Rapidﬁre, which is only £5 more. You’d have to really like that clunkier click to bother switching from stock Shimano though.