trust me, you get a dovii, long term you looking at atleast a 300 gallon, awsome fish with great attitude but they need ALOT of attention and a huge space.
Are you planning on upgrading, or just keeping the 120 long term? This plays a huge role in whether or not you should even consider a dovii. Jag male may be OK in a 120 for life, although even that could use an upgrade when he's pushing 15".
If you're staying with this tank, I'd say jaguar. If you plan on upgrading and knowing that you will need a much bigger final tank, then you can't go wrong with a dovii.