I'd recommend a mid-end loader. I do caution you to stay away from the Evolution II or III (we call them eggys) they're not as fast as they claim. A nice revolution is a great loader that is proven and I really haven't heard any bad about the FASTA loaders.
If you like. Really all barrels shoot fairly equal, so go looking for something that catches your eye looks-wise and isn't to expensive.
I generally go for the cheaper mid-end paint that my field stocks when I play. The accuracy and range of it are good enough for just having fun at the field.