The biggest issue I had with Bendis' initial Mighty Avengers was the story ran parallel to New Avengers, and are impossible to line up chronologically with that book despite the fact he was writing both of 'em! And then all the Secret invasion supplements...good grief!
New Avengers was what got me buying comics again, proud to say I have issue 1 - the Finale.
Also have the full set of Invincible Iron Man that started with Extremis and ended with the War Machine arc. I have Fraction's run up to issue 18.
I was very consistent with Brubaker's Cap until issue 605 or so.
Going into "Now!" I plan to start Uncanny Avengers and All New X-Men, Iron Man and Captain America, and Superior Spider-Man. I will just be testing the waters with UA, ANX, and Cap...see how those stories progress through their first arcs.
I need to fill in the gaps in Iron Man and Cap. And I will continue working backwards on Spider-Man, as it has become my goal to own every issue of Amazing. (The rest will follow. Already have the full run of Friendly Neighbourhood Spider-Man! 1 title down, 90 to go!) I don't want to get to many new Now! titles so I can focus on those back issues.
On the DC end, my 13 issues of Justice League, Action Comics, and Batman are my longest DC runs ever. I am dropping AC after Morrison leaves, Superman isn't a personal favorite and I'll get to see him do his thing in JL. I am going to work backwards to get the rest of Morrison's Batman which I've started in Trade. I wanted to continue with Animal Man but my shop doesn't get those in consistently.