I really like the 15g it looks great, just my taste.
the 10g I would put more javas, I love java fern, so easy to take care of.
The hex could use some attention, what is that little black thing at the bottom, maybe you could fix it up for a dwarf puffer, that is what I plan to put in my 6.6g, they love to eat snails too. Or maybe some shrimp, do you have plans for it?
I love your little super nano, I have seen some really neat super nanos out there, maybe I need one... hmm...
Great tanks, would love to see pics of the fish!