i use both in combination on my machines... and don't forget the r1-10 value for speed/precision (run a high feedrate and you'll see the difference in the speed and in the definition of hard edges on a 3d contour
there are lots of system and servo parameters that control your speeds in various ways... i'm no expert but i'm learning...
i run all my machines with g8p1 called in the toolchange macro... and the rigid tapping macro cancels it for tapping
i run g05.1q1r5 by default in the same way on everything except the 0-mc and 0-md which don't have AICC
i sometimes modify the R value depending on the 3d path but its fine for most everything at R5
two of my later (2006) 18i-mb controls have AI NANO (despite the manual saying its only on the 16i) but i can't seem to enable it on the one from 2002
it smooths out the toolpath better but doesn't speed things up much... its called the same as aicc, with g5.1q1r5
the 0i's i have don't have aicc but use the g5.1q1 code for AI APC (ai advanced preview control) which acts about the same but not near as fast as the aicc or the ai nano