My girlfriend is just a little over 5'5" and 105 lbs. She didn't have a problem per se with a 7 ft hose, but it was a little too loose on her. A little extra was always hanging out and making the hose more likely to come loose. She's getting a 6.5 ft. one, but could probably get away with a 6 ft. hose.
About "it's for you buddy argument": Well, you are the one using it and wearing it 99.99% of the time. But if you are diving in an overhead environment and it's so tight that you have to move in a single file, and your buddy experiences a true OOG, then he exits first so that you don't accidentally loose him (i.e. you don't want to look back and see he's not there anymore and your longhose is just hanging in the breeze).
If the buddy is really tall, then you may need that extra 6-12", or even that may not be enough to comfortably swim in a file with him first. OTOH, that situation is pretty unlikely, and somebody dying because they couldn't make it work without that extra 6" is pretty damn unlikely, so it may be better to just go with the hose length that comfortably wraps behind or in front of your wing, under the can light, across the chest (maybe helping to stow your lighthead), behind the neck and into your mouth so that you can still move your head comfortably but don't have too much loose hose hanging behind you (you push the extra behind the can light in general). So take your pick. Stop by a shop and try out a few different lengths if you want, or just get the 7 footer.