I honestly prefer GalCiv 2 over Stellaris because it isn't so overly complex! GC2 is my favorite space 4X of all time. I love building custom ships in it, and the AI is in my opinion the best AI in any 4X game ever made.
I've not bought GC3 yet though. I will someday.
As for refunding Elite, nah. I've more than gotten my money's worth from it. Now, whether or not I put any more money into ED entirely depends on what the Q4 exploration improvements end up being. I have a list of store items I'm waiting to buy until I know what those Q4 changes are.
That's actually me too most times I go for 4X gaming.

GC2 hits a great sweet spot in complexity and depth but without needing vast investment unless you want to, and I agree that the AI ranks up with the best of them and provides great games that don't feel like you're against a gang of derps (unless you throw in random smarts for max chaos). Stellaris is super deep but it can be dauntingly deep to start into sometimes. Nobody should pass it up though if they're into empiring around and don't want to Crusade any Kings.
But yeah, a huge fan of the shipyards in GC2 myself, cosmetically, engineering-wise and on a mass-production iterative design level. At one point during a seriously heavy GC2 era playing largest-galaxy-slowest-growth games I designed a 7-digit ship registry coding system to keep track of my prototyping, specialist designs and iterative regular fleet lines, along with operational data at a glance; the ship tinkering is great and can provide a fun focus inside the game proper. Had one game where a minor faction awakened one of those special-event pangalactic fleets of ancient evil that wiped out half the known galaxy, and I had to retool my entire empire from my original designs to survive and then overcome; good times (except for the billions of lives lost but hey, 4X in spaaace).