Well I'm gonna be negative again (apologies to anyone whos favourite run I poop on)
I do NOT like Miller's DD.
I guess it depends on your preferences and how much you are into older (lates70s and 80s) comics.
Compared to the regular output it has a very mature tone and storytelling but coming from more modern comics (especially reading Bendis' first) it felt very uneven.
I think it tries to be serious but it still manages to be a wacky superhero book .
I remember enjoying the middle part, but the start was very silly, I didn't like anything to do with ninjas (again, felt silly) and the whole big Electra thing was super rushed.
On the other hand I really like Man without Fear (which flashes out the whole Electra thing and give DD the "black home made costume" origin) and of course Born again was really good.
You can start with Bendis if you want a more modern run and then go straight to Brubaker (those 2 runs are the best IMO). Shadowland is best to avoid, most people agree on that.
Waid is polarizing, mainly because his run was a huge tonal shift. I've found it entertaining for a while when Martin and Rivera was doing art, but then I've lost interest.
Read like 20 issues of Zdarsky's (current run) and it's really good so far.
So my recommendations would be: Man without fear and Born again from Miller.
The short Kevin Smith run (precedes Bendis and has one important thing for continuity, not essential but not bad. The Echo story right after was horrible tho IMO).
Bendis, Brubaker, maybe try Waid and see if you like it, Zdarsky.
As for Ultimates, I think the only good books are the first 2 Millar volumes and USM (although I've tried to re read it not that long ago and didn't last 10 issues so you know, take my opinion with a grain of salt).
Speaking of teen superheros and Marvel (cus you're reading USM). Have you read BKV's Runaways?
If not I think you'd like that and also the current Runaways from Rainbow Rowell (I haven't read anything inbetween and I was fine and really enjoying Rowell's).