I dragged my sister along on a ride today and when we stopped for a snack break she eyed my panniers and asked if they were new..."they're not the ones you took on the bike tour were they?". Yes, they've got over 13,000 miles of touring on them and they still look new (thanks to rain covers), I bought them early 2004.

I've got Arkel GT-54s and GT-30s. I'm a big believer in getting the best you can afford to buy, just because I hate buying something and then having to upgrade it and replace it in a few years when it wears out or no longer suits my needs. Granted, these Arkel babies are expensive but they work well and have a lifetime guarantee, you will probably never need another set of panniers unless a koala tries to rip it apart looking for gum leaves or something.

1. The pockets and zips are a big advantage, I've traveled with guys using Ortleibs and when I have my tent up and they're still unloading their entire pannier just to find the tent pegs that they placed at the bottom of their panniers...they always eye off my panniers a little enviously (while I'm already well into my recovery meal for the night).
2. Lifetime guarantee; I had a rack support clip break in Alaska (I believe the bag was slightly crushed when it was unloaded off a train with a forklift, as the other clip broke several years later, but I've had no problems with any of the others) and Arkel sent me replacement clips and spares and a tool via overnight delivery, no charge (though you could say I've already paid for it in the cost of the bags).
3. Durability; like I said before, I've done a lot of miles with these panniers and they still look almost new. No problems with zips or any seams breaking. A squirrel once chewed through part of one of the rain covers but the little bugger also ate a bunch of my handle bar tape so I guess they're not choosy.
4. Visibility; the bags come with heavy duty reflector strips on it (so do the rain covers) and after over a year of touring and exposure to sun and rain there is no sign of wear to these. The rain covers are bright yellow, and apart from getting supposedly almost mistaken for a moose by some cretin of a hunter in Canada, there was no trouble seeing me in any kind of weather.
5. They're not fully water proof. The rain covers do a brilliant job but when it is flooding down you will inevitably get some water in the bottom of the panniers. All my important gear (clothes, camera) were in Arkel dry bags which did the job they were meant to. The bags dry out very quickly once the rain stops as you just take the rain covers off and maybe unzip the bags and the wind tends to dry everything quite quickly. My panniers tended to get more wet from putting wet tents and wet clothes inside them rather than the weather itself. I'm not sure how Ortleibs go for letting out all this dampness?
6. They're big and so I tended to fill them up with way too much stuff! But there's very handy pocket bags for money, toiletries, and even a sleeping mat.

Just my £0.02 worth. If you want to see pics of them in action, check out my website on the footer below. I think Arkels are really worth getting if you plan to do a lot of touring and can afford the expense, I don't think you will regret it. I got mine because of a similar post on these forums a few years ago.

Cheers
Leon