I have enough MP to buy a DLC pack for Fallout New Vegas. I want to know which one might suit me more in your opinion.

I am a level 30 who specializes in Guns, Speech, and all around weaponry. I use the Anti-Material Rifle, YCS-186 Gauss Rifle, Light MG Drum Mag when I feel like it, Hunting Rifle all possible attachments, lots of C4, the Weathered 10mm Pistol all attachments, Love and Hate, and Oh Baby! (not all at once, just when I feel like them).
I use Combat Armor Reinforced Mark 2, and I have every follower in the main game waiting in the Lucky 38 Casino. I play on Hard difficulty but not hardcoe. I am a completionist and like to earn achievements and trophys, so I would prefer one with a lot of achievements and great gameplay. Any feedback would be really helpful, thank you!

Browse YouTube for some reviews on each of the DLCs. I think they all add 5 new achievements and everyone has different opinions so its hard to say which you would like best based on your post. Lonesome road is challenging. Old World Blues is filled with a bunch of neat things to find and awesome loot. Dead Money is survivalist. Honest Hearts is, to me, a lot like the main game. If you plan on getting all DLC eventually, I would start with either DM or HH.