I'm figuring it would've been the most evolved but sometimes games go too far and screw up their sequels (yeah I know Androsian War sucks)

I prefer BI2, really. I disliked the blind turns of the opponent, the increased amount of useless animations in the menus and the filmed sequences to tell the story are both super cheesy and way inferior to the in-game narration of BI2. But, really, just try them all. Each BI part has it's own charm and each, including History Line, is sufficiently different from the other that it's worth spending time on them :).

Exactly my thinking. BI2 + addOn are the best parts of the (original first 3 parts) series. Although the BI1 and especially the "moon" levels (data disk2) will have a place in my memory. BI3 can be annoying sometimes. The videos slow down the gameplay A LOT (created a thread on how to get rid of them..) . Some units are absolutely unbalanced, some maps are unfair because of surprise enemy unit spawns (SAFE OFTEN!!) and the AI is .. well.. lets say easy to distract. But this also counts for your allies, which makes them stupid cannon fodder at best.

Incubation is a extremely well done spin-off and andosia is crap. two different games by two different companies mixed into one. for me, its an unplayable mess. If I remember correctly, it was the first big game release after BlueByte was sold to Ubisoft then.. says all, I think..