I was a huge fan of the old Space Hulk - but the new one didn't really grab me.
GalCiv 2 really is just Civilization 3... IN SPAACE! Turn based, tile based. So kind of old fashioned, but with all the expansions has a lot of variety, each race has its own tech tree etc. GalCiv 3 disappointed a lot of people by being not much more than a re-skin of GalCiv 2.
Sins is interesting as a 'Real-time 4X'. Best feature is really just lots of good looking pew pew between starships.