I run my base defense as Nickel Wide-9 because it's extremely effective at stopping the run if you have a good front-4.
The LB's I usually use are highly athletic, converted DE's because I want them to have the STR to rush the passer and stop the run (BSH + high STR means they come off blocks easier). High SPD/ACC also allows them to cover the pass reasonably well, or at least close / catch up and make the tackle if they screw up the coverage.
They're also typically taller than your standard LB, which can be helpful in some rare instances.
There's also a sub-package where the starting LB's replace the DE's. You can use this to immediately sub your DE's out of the game if they get fatigued, and this way the stat drop off from your starting DE's to your backups isn't significant since your LB's are also converted DE's. Keeps a constant, Elite pass rushing presence on the field at all times this way.