I miss one thing on DMM though.

Autorun. Sometimes it's n1 to be a lazy guy you know

Nutaku has an Autorun Option.

About the larger Pull Pool:
Yeah it's more difficult to get a specific 5* because of this but larger pools means more good 5*.
You have more 5* with good Abilities on DMM than Nutaku.

Lets be honest: How often do we get the Girls we actually want anyway (without whaling)?

And if you are an occasional spender like me who only wants specific 6* the DMM Version is much better because they have more 6* Choice Deals than Nutaku.

It's simple:

If you are F2P, Occasional Spender or Semi-Whale (Dolphin) DMM is far superior.
If you are a Whale or Hardcore Whale Nutaku is far superior because Nutaku has more Special Deals (basically every week)