To a counter, an empty table is better since you get more play per time spent at the table. Since you have the advantage, the more hands you are able to play gets you closer and closer to your EV.
However, to the non card counter, playing at a packed table is better. You get less play for the time you're there, but if you're getting rated for comps the clock still ticks, so you effectively wager less money for the comps you get. Plus if you add things like free drinks into the equation, pretty soon the game is almost +EV when you take into consideration the -.40% you lose if you play perfect BS as well as the $5 Heineken you get every 10 minutes sitting there........
My personal take is this. I don't play enough times per year to worry about counting (nor do I have the bankroll required or the time to invest in learning it). I go to Vegas once a year and Atlantic city probably 3 times. I play for the lowest stakes possible, since I'm a poor college student. I play perfect basic strategy and play at the tables with the best rules I can find. When I figure what my -EV is for playing $5 blackjack for an hour, then look at how much the 3 beers I had over that hour would have cost me at the bar, I end up +EV. Plus, figure in the dealer mistakes that I've profited from and some of the hand interaction plays I've done, and the game isn't all that bad.