Id say it's mostly personal preference. In the old days the optical mice jumped back if you whipped em around in CS, but it doesnt do that anymore.
I personally use my mx500 and am not trading it in for anything until theres real improvements in mice...which i dont know when will happen.
I do know however that between myself and my 3 roommates, two of us had logitech mice (one mx500, me, and one mx300), and two had intellimice. by the end of the year there was still my mx500, 2 mx510's, and an mx520 or whatever the new one is thats grey.
just .02.
EDIT: btw, the reason they switched to the logitech mice was that one mouse kept getting "disconnected" (or so windows thought)...happened like every 5 mins or so and stayed that way for about 20 seconds then reconnected. The other one had a weird double clicking thing where if he clicked once it would always double click...which made playing cs quite weird with bursting....
My vote is for the logitech line, but some like the button placement of the microsoft mice better.
As far as acceleration, i know its something that can be turned off in the logitech software. I dont even have any software installed on my comp (mouseware i think its called), and i dont feel any accel and can play at a pretty decent level of play (cal im/m equivalent).