For all positions on defense? What are the most important attributes to look for ?
The most important part of a 34 defense in my opinion is the defensive line. You only have 3 linemen, so they have to be able to hold their own. You want guys with high strength and block shed. You also want to look at weight since that matters a lot in player interactions in Madden.
The next most important part is having OLBs that can get to the QB with either Power Moves or Finesse Moves. If you're a higher level player and you're setting up blitzes designed to get free pressure, this matters less.
Yeah Rocketz is pretty spot on. Main difference is DL/LBs. In 3-4 you want your defensive ends to be big and able to stuff the run (think Cam Heyward, Aaron Donald, etc) as opposed to a 4-3 where your DEs will be more of pass rushers (such as Danielle Hunter or the Bosa bros). Additionally, in 3-4 your outside linebackers will be your pass rushers (TJ Watt, Zadarius Smith) whereas in a 4-3 your OLBs will be playing off the ball more and are practically additional MLBs. And that brings me to the MLBs: in 3-4 you need two good MLBs, but you’ll only need on MLB in 4-3 as the outside backers will be playing more of a MLB role
Edge rush for your d ends