Cost of Titans vs everything else

On the other hand, per fleet supply the titan uses less slots, and as it levels up it permanently becomes stronger even if it gets destroyed. Also the research, labs and shipyard are a one time fee, I think its fairer just to include the base construction costs, as in a long game you'll probably need to replace both the carriers and the titan so those become less of a weight on the total.

But you're right, bombers are still too powerful against far too many things. Titans weren't supposed to be countered by bombers, that's why they have antifighter weapons, but with enough bombers it becomes easy to destroy anything quickly. Personally the only way I think this can be fixed is to give flak or fighters (or I suppose even the titan flak guns) AoE damage, but that would hurt fighters just as much if not more.

I feel is that they should keep the cost of making a Titan relative to their experience when being made. Not only would it justify the retention of the experience by Titans, but it would also make you protective of your high level titan. Not too much cost variance, but still should be there. Like, in one game I was playing, I was on the verge of destroying an Advent rebel empire. They only had like 3 planets/asteroids left. I destroyed their level 6 Eradica (it took down a lot of my ships before it died, damn invulnerable power -_-). But then their allies attacked me with a huge fleet, so I had to retreat. I built up my fleet again, BUT by then they had built another level 6 Eradica. With their 3 colonies, their economy should have died. But here I saw another poewrful Eradica, who again took down ships (less this time, had made more carriers and bombers). Their allies weren't helping my cause either.

I'm not saying cost scaling is absolutely necessary, but just an idea. It justifies retention of level and XP.