Trinity isn't my favourite map but it is OK once you get past the front line stage, Beta2 is my pet hate. The problem with Trinity though is the time it takes to win. At least with any other map that you dislike it is gone in a few days.
It wouldn't be hard to make Trinity a better map. The choked front lines at the start position are the biggest issue. Unless there is a CV in range you only have one pair of airfields in close proximity per side, plus A1. This benefits the defender to the extent it is hard for an attacking side to make progress. Also, at the start position you often get only one picker infested furball to fight in, there is no choice of where to go.
This could be easily changed by reducing the height of the border mountains, which is simply a matter of HTC changing one number in a text file. So if this number was reduced to 1/3 its current value, it would reduce all the land altitude to 1/3 height over the whole terrain, thus making fields over the whole borders' length accessible. The main benefit of this approach is it would need no further bug testing.
Another way would be to cut two or three A1-style canyons through the mountains per border. Or add chains of island bases across the seas. This would be a lot more work though.