see my comment above yours for my answer. They're all good. HH is standalone, while the other three are linked by an overarching metaplot. They're all related, but peripheral, to the main game.

Lonesome Road should be played last, perhaps right before Hoover Dam. I usually see it recommended that you do DM before OWB for story reasons, even though DM has a higher recommended level, but imo you could do them in either order.

Note that they do kind of mess with the balancing. If it's not too late, I would highly recommend using a mod that puts the level cap back down to 35 or 40, as otherwise your skills get so high that skill items aren't even useful anymore. (Even better, there was a mod that let you level up manually, and leave skill points unused while still getting the fun perks, but sadly it broke and been has been removed from nexus indefinitely). Completing DM right will give you basically unlimited money for the rest of the game, and OWB will give you what is easily the best endgame energy weapon
(the unique LAER), along with a steady supply of ammo that will allow you to use OC and MC for the rest of the game..