The Buddy Pocket Reel
http://www.apvalves....(sept 2005).pdf has always served me well, with one caveat that I'll come to in a moment. What I like about it is that the line/spool is totally enclosed, so line can't spill off and get tangled with something else, and that it has a positive lock every revolution strong enough to hang on. Since I got one (several actually - I became a dealer for them and other AP Valves products) I have never found the need to look for any other GP reel.
The caveat - I have found with all of the ones I've used that after a while the reel begins to tighten up, to the extent that it becomes difficult to use safely. The problem is that the screw holding the whole thing together doesn't rely on friction, but on reaching its end stop. As the plastic reel warps slightly in use this screw becomes too tight, causing the reel to jam. Easily resolved - remove the screw and disassemble the entire mechanism (quite easy, given care not to drop the line). Grease all sliding parts (apparently not done from manufacture) and push paper or anything else suitable inside the threads so that the screw doesn't go quite as far before it tightens up, leaving a bit of slack. Problem solved, and this is a one-off fix that never needs repeating. I've used the same Pocket Reel for 8 years and can't fault it in design, operation or robustness. The only other issue is that they aren't particularly cheap.
