The Galaxy is better than the KEV hands-down in 9/10 of situations. The longer cloak + mines is more than enough to make up for the KEV’s mid-range phaser advantage.
KEV’s biggest advantage is in Gold earned per second, since you’re not paying for most of your torps.
Both ships have to stay near sb to survive very long, though I’d say the Galaxy can venture out further since the cloak is so much better, and the energy cost/warp energy is cheaper. The KEV has to get AM more often too.
I honestly wish I could have buffed the KEV (along with several other “classic/standard” ships) to be more competitive in Delta… It would have been confusing though, to have different specs for the same ships in different quads.