When comparing a $100 closed water cooling loop to a $100 air cooler, which would yeild better performance? My brain tells me most of the time it will be the air cooler cause its much more simple so most of the money can go into the quality of it. Also on a side note, is it okay to take of the stickers on a power supply? I mean I know it won't harm it but what if I have to send the PSU for warranty? I really like the look of a clean PSU without any branding.
Unless you plan to game or fold 24/7, an AIO water cooler will not give you appreciable gains vs. a good air cooler. Even the lower price units like the Hyper 212 and Xigmatek GAIA will cool within 2-3* of a sealed w/c.
As far as the stickers go, there is usually one small sticker over one screw that says "warranty void if removed" or similar. Leave that alone and remove the rest and I think you would be safe.