Boonex and UNA is the same team. UNA was first planned as a direct upgrade for Dolphin (Dolphin 8, originally), but due to the volume of changes and some core architecture difference, we had to release under a new name. Dolphin is now renamed to Dolphin Classic and is being phased out. 

We see UNA as a superior platform, by design, but it does take a while to achieve feature-parity with Dolphin, especially if you rely on 3rd party modules. Since UNA 9 practically all main Dolphin features are available in UNA. From UNA10 and further, we will have enough functionality and 3rd party modules to migrate most Dolphin sites. 

If you are only starting, definitely use UNA.