Depends on what order the routine is in and how much time I have in between my skills. Typically, it is whatever is in the middle of the routine.
Last year I had a lot of down time, so everything was easy cardio wise but baskets were hardest mentally (I'm terrified of heights and I had 3 ginormous male bases).
This year I anticipate group tumbling and jumps to be the worst. We are doing it right after elite stunts and before jumps.
for my kiddo it's always the tumbling...either jumps to standing tumbling or running tumbling. thankfully her coaches this year do not have her in the running since she a lot in other parts of the routine...so if she can hit those 4 jumps to tuck then she is good to go!!!
I voted for stunts...Seriously, as a spectator, it just appears that this is the area of the routine where often you see the most errors. Typically, stunts, which I am also including pyramids, tends to require the whole team to work collectively together too...jmo