I play both and while it is a matter of taste, DA adds a bunch of stuff which sometimes
I like and sometimes I don't like. On a huge map, DA for me tends to give a longer game, my space ships are slower and more expensive. The new planet types--some days I like them, some days, not.
DA badly needs a Galactopedia or something to make improvements more transparent. I don't think the current Galactopedia will work on DA although I have heard people say otherwise.
In DA, it seems that all improvements make things more expensive. I think with research and miniturization some things should become cheaper (maybe older things or with minitizuration).