You have a nice range of choices, granted about half of them are repaints.
Generation 1/2They say the original is always the best, so this is a no-brainer. He is simply iconic, but alas, also knocked off more times than you can count. There are even fakes with authentic looking G1 boxes! Should you want a G1 Devie MIB, get it from a reputable, experienced dealer.
The Generation 2 version has some color changes, from green to yellow or the rarer orange, here's where you need to pay attention. AVOID the yellow ones from Europe, as they don't have the combiner pieces
and have some connectors removed.
Action MasterNon-Transforming, comes with a transforming scorpion. Ok, I'm done cheating here, moving along...
UniverseThe Landfill repaint, I consider him second best. Consider this: Landfill on his own was a throwback to Diaclone's Construction Robo, from which Devastator was derived, so it's fitting in more ways than one. He came in two sets of two figures, as a Target exclusive. I want both Landfill and him!

O, don't mind that Scavanger is all purple instead of green.
Universe Micromaster (or Destron Sixbuilder)
As far as accuracy goes you can't go wrong with this Micromaster Six-Combiner. The vehicles are the same, colors are correct, 3 of the original names are used (repurposing or renaming does wonders), what more could you ask for? Compared with the original G1, the Micromaster actually looks a lot more streamlined and organised, and has the same articulation to boot
Classics Constructicon DevastatorRepaint of Energon Constructicon Maximus, here's where things feel a bit iffy for me. Maybe it's the fact it has only 3 molds total: Excavator, power shovel and crane. And the opposite color polarity of each "twin" feels a bit like cheating to me.
Movie Constructicon DevastatorI hope you can handle 6 non-transforming Tonka-like vehicles combining into this hunk of plastic. I can, but I'm gonna wait until he gets clearanced.
Movie Legends Constructicon DevastatorInstant buy. If you want only one Devstator from the movie, get him.