I took it out from the bottom last year, my first time doing that, been lifting from the top 30-40 times before. If its only engine work, I still would remove from the top, since it can be a bit tricky to remove all the suspension parts, and the front end has to be relaigned afterwards. But if you gonna do anyting with the suspension/brakes/steering also, removing from the bottom is highly recommended, once you got the T-bars, UCA's and K-frame bolts out its a smooth ride.
Removing from the top is easy also, disconnect everything on the engine and tranny, remove the tranny mount bolts in the rear, loosen the tranny mount from the crossmember,(4 bolts) leave 2 bolts in though. Connect the engine lift, good thing if you have one of theese (picture), so you can adjust the angle of the engine/tranny (it works anyways, but those liftblocks are great). Then put a jack under the tranny, remove the tranny mount completely from the crossmember (the tranny just rests on the jack now, lift the engine a bit so it slips out of the motor mounts, lower the tranny all the way, adjust the angle of the whole package and carefully lift it out. Once the engine is high up, you have to lift the rear of the tranny over the radiator support while rolling the engine lift backwards. If the car sits too low, its hard to the the right angle of the package, I like it on jackstands so I get a good angle and can get under to get the tranny mount out easy. The other picture shows a good angle, that was my first Challenger (early 80's)