I had the same conundrum earlier, as I'm planning my first tour this summer. After a LOT of weighing, reading forums here and journals on crazyguyonabike, I got the Ortlieb front and rear. I want to do this a lot, and near as I can tell, these are the tops, and last a long time.

The way I look at it, for not a huge amount more than an average set, I can buy the Cadillac (that phrase used to mean something!) of panniers. To me, it didn't make sense to go cheaper (but then, I could afford the extra at the time)