My favourite fives are my two Sei headlesses (one fretless Original, one fretted Flamboyant), and my Antoniotsai.
I do recommend headless for fives, even more so than fours, as you get rid of a lorra lorra weight and those hideous headstocks.
Oh yes, reasons. Playability. It took me quite a few goes to find a five that I was anything like as comfortable with as my Warwick Thumb 4 - a JD NT which has a very slim and shallow neck profile.