Personally, I wouldn't choose any of those hammocks as my first. The first four are beginner hammocks, and I believe they're all kind of short, and I prefer longer hammocks (10 or 11 ft).
The MMG Bivy, I believe, is for people who fear they'll have to go to ground, a fear I've never really shared. However, it does have bug protection, as I recall, unlike the others.
How tall are you and how much do you weigh? Are you going to camp in bug season? Are you looking at these particular hammocks because you have a budget? A little more info might help folks in helping you.