I prefer regular speed, since it keep stacks deeper, which allow for more play and skill edge. However on
pokerstars I have noticed, that regular speed tournaments tend to play 20-30% less hands per hour than turbo tournaments, presumably because people are given more time to act. This I actually find rather annoying, because often you see people use their entire time allowance just to make a trivial decision preflop, and it really slows the action down. And I am not even talking about bubble play here. This happen already in the first blind levels.
This incredibly slow pace, where a regular tournament on Stars might only play 40 hands per hour, also negate some of the effect of longer blind intervals, since the important is, how many hands you play per blind interval, not how long it last. Cuppled with the excessively large fields, which make a regular tournament last 8 hours or more, there is certainly a case to be made for playing turbos on PokerStars.