Honestly there isn't a bad strike and I actually enjoy them all. But here are two factors. First, repetition is boring as hell and annoying. If we keep on getting the same strike we will end up hating that strike for a little bit. Second, time consuming doing a strike. Time consuming I mean as in taking longer than the usual to finish I strike is annoying as well and the perfect example is the undying mind strike. The undying mind strike is really annoying because of time consuming at least in my experience and that's the reason I leave most of the time. The strike itself is not difficult at all but it does take a bit more time than the usual strike. Too many ultras on those stairs and to a point it seems infinite even with unlimited supers. That gets me annoyed and that's the reason I leave most of the time from that strike. But the undying mind as a strike itself is one of the best.