I always preferred the back of the hall. Here, I could go to sleep, read the latest Awake! and Watchtower, or just go to the restroom.
Front
No one can disturb you at the front. You can listen "without distraction" or if you are really spiritual you can focus on the speaker the whole 50 minutes and absorb everything.
Back
For slackers, microphone dudes, DJ's, parents and df'd ones. Plenty of distraction here, plus trips to the rest room are easier without those watchful (and sometimes disapproving) eyes. Sitting at the back affords the ability to sometimes nod off. (some can actually sleep with their eyes open). It's easier to pass notes too.
Middle
Can't do much here, as there's those watching the back of you. I never liked the middle rows.
End of the row
If you're at either end of the middle row of seats, you can see who has studied their watchtower and who hasn't.
Did you ever heed the counsel to sit somewhere else?