Should I get 5* Malevolence, then 7* Negotiator, or just focus on one? Already have Tarkin/Geos fleet.

So I am a pretty new account. I'm investing heavily in fleets and so far have a pretty good Geos fleet under Tarkin. My original plan was to finish my Tarkin/Geos fleet and then work on getting Negotiator to 7*, so I'll have 2 fleets to use. But I saw someone suggest taking my Tarkin/Geos, upgrading them into a 5* Malevolence fleet, and then going for 7* Negotiator. I know Malevolence can be good at 5*, but I didn't know if the trade off of splitting GET between the two ships is worth it.