Any of them in
New Orleans on the lake will be fine. SouthShore has the best
liveaboard facilities and is probably the easiest to get to the French Quarter from, but is located pretty far from everything else.
There are three other
marinas I would recommend first. The Orleans
Marine (also called the inner harbor), The New Orleans Municiple Yacht Harbor (the outer harbor), and bucktown marina.
The outer harbor still hasn't been fixed from Katrina so it doesn't have
power, the slips are dangerous, and they have limited slips that can even be rented out. I would steal clear.
The inner harbor is really where you want to be. Good slips,
power,
water,
live aboard amenities, etc.
Bucktown is fine, and is pretty much brand new. The problem is that it's isolated from the
marine suppliers that the inner/outer
marinas are built around. I know nothing about it's facilities except that whatever it has is pretty much brand new.