I have used both fins and I have to agree that they are both very comfortable.
Tusa fins: I enjoyed these fins a lot, and they are so comfortable I didn't even notice I was wearing them. I noticed that they didn't provide much power when surface swimming, so those long swims on shore dives before dropping to a good spot will take some time.
Apollo fins: I like the Bio-fins better than the Tusa's; this is due to the added power I get out of them in conditions with surge and strong current. Surface swimming w/ them is great, although I used these mostly for boat dives. They are comfortable and feel very "fluid" like extensions of your feet. Very nice.
I would say that price would be the deciding factor between the two fins. If you can't afford the Apollo Bio-fins, get the Tusa's--they are comfortable and great all-around performers. If you have some extra scratch, spring for the Bio-fins--you won't regret it.