A word on POR15, it doesn't hold up to sunlight very well! A friend put it on his Land Cruiser FJ40 and it has faded quite a bit.

When I find a half-decent used bike to refurbish, I'm going to strip it with aircraft stripper or similar, then have my brother in law paint it (he paints cars for a living) and then I'll mask it and have him paint the details too. Blue/white

Now for a commuter beater, I think hammerite or POR15 or just about anything would be good. Or, you could do like I'm doing on my wally-world bike, and cover it in stickers