Figured I'd add in my opinion since I did vote too (I went with Netflix) .. I had numerous issues with Blockbuster, several times they claimed to not receive the DVDs (this was pre my HD DVD) and several times they would ship movie ~30+ on my queue, rather than from the top (numerous times, generally once per week). I figured it was okay, but then after they took away the instore rentals (wasn't grandfathered in, apparently I rent too much) and the slow shipping, I dropped Blockbuster since the value wasn't there due to slow shipping and lack of instore rentals. I figured I'd give Netflix a go, and thus far, I'm pretty satisfied. Their instant viewing is pretty poor, unless you enjoy TV shows (I don't, but its alright since I didn't get it for that) but I can ship my movies out and they're generally received within a day, and sent out immediately. Can't say I'm disappointed at all since its very quick turnaround.
I do have one complaint though, why are their envelopes so bulky? I had to fold over the sides (the parts where the DVD was not) to get it to fit into the mailbox..