Mostly what was said above;

1) Nutaku was the first one I played and have my most developed army

2) I have spent a lot on Nutakus Aigis and would hate to give that up

3) It is in English and uncensored art (I can't play the 18+ DMM version anyway unless I use VPN which I don't have membership too.)

Nutakus Aigis has been picking up too, even though DMM has much more on offer, I find myself enjoying it more first on Nutaku and don't feel the buzz as much if I play it out first on DMM where I can't read all the dialogue before playing maps/events on Nutakus Aigis (I can't read Japanese but would very much like too.)