I've been playing the game for a bit over a year, and I just started working on my 3rd army not that long ago. I usually tell myself that I am not going to expand into a different army, than fall upon reading their codex one way or another and become enthralled by them. However, I tend to play armies that aren't really "hot" at the time. My first purchase was Eldar, and that is just tradition for me. Ever since I've been playing any fantasy oriented game I'm always the Elves, and DoW1/2 really got me into Eldar full fledged.
Before dumping into an Eldar army though I had thought about going
IG but ultimately couldn't resist the pull of the Craftworld. However, eventually I wanted to switch it up more than the Eldar codex could offer, and I found
IG as a great solution. However, I hate playing
IG as the Chimera mech spam you commonly see. I picked
IG to send a bunch of bloody men to their doom, and that is exactly how I play them. Giant fearless (figure of speech, just
LD 10) blobs giving their life for me...err....the Emperor.
Black Templars are my latest venture, and once again an Older Codex. Something about their Fluff grabs me, since Space Marines have always been cool but a bit to campy for my tastes (in their Ultramarine/Vanilla formula).