I like tank #4 the best, or I think it has the best potential. It needs more plants, but I love the wood.
#1: I'm not a huge fan of the rock layout and moss balls. I like more natural looks.
#2: I really don't like hexagon tanks at all, I say you sell this one and reinvest the money in a new tank or some plants for the #4 tank.
#3: I like that it is like a jungle. It does seem to have a huge variety of plants, I think less varieties would be better though.
Do you have plans to make some changes to these tanks? I think if you do, focus on 1 tank at a time and get it the way you want before moving on to the next tank.
What do you think of your tanks?