I intend to use tape when I buy a rack, so as of now I only have experience with UTHs, that said... A few observations I've had

-I use ultratherm UTHs... and have used others. I prefer the ultratherms to use on tubs because they will not heat up enough to melt a tub, which seems safer to me (even using with thermostats).

- The ultratherms don't have a "sticky" side, so you attach with metal tape, just like heat tape.

- For some, wiring heat tape at home isn't feasible and if done improperly, can lead to overheating / fires. This is one of the main reasons I haven't tried it yet.

- It might be impractical to purchase tape and connectors / wire the tape for a small single tub / tank like a 10gl. For that use, a UTH seems more practical.