BeerBorg

Any particular reason?

Ball locks appear to be more common at least in my part of the world. Here's some interesting reading and a short video: http://www.cornykeg.com/store.asp?pid=29969

Ditto. I see a lot of pin->ball conversion kits for kegs but not the other way around. If just using at home it probably doesnt matter, but if you plan on going to keg tastings and such ball would probably be the way to go.

Pin locks are shorter and wider, so usually you cannot fit as many into the same footprint, but they are cheaper than ball locks. I went with ball locks for my system because of that - I can fit 3 ball locks into my keezer, which wouldn't work with pin locks.

If you've got the choice, I'd go with ball locks.... Connections are more common and most NEW kegs are ball lock so if you ever add more to your collection, you don't have to mess with switching out hoses.

That being said, if you find a Craigslist steal or a bargain somewhere on pin locks, have at it. They do the same thing, they just use different connections to the hoses..... So you wouldn't want 5 ball locks and 1 pin lock, that would get annoying.

The fact that all the new kegs I've seen were all ball locks is a good reason to stick to ball locks. Never even thought of that.