How many cells are you using? If you are on 6 cells, you need an UBEC anyway.
Personally, i got bad experience with the aquastar. It does have a loose water coupling (usually) that needs to be fixed before you run it, otherwise it will leak water internally, and short the electronics inside the ESC.

The HK 200A is way better. It does also need a fix to run its rated 200A, but since it apears you arent going to use it for more than 120 (looking by your other esc selections) thatwont be a problem with a HK 200A.
Anyway, the problem with the HK 200A is poor thermal connection between the heatsink and the FETs. But its an easy fix, and its not even necessary if you arent going to push the limits of it.