1) original Red Box Basic/Expert sets aka B/X aka Moldvay/Cook
-I love the flavour this version oozes, I like a lot of its rules, as messed up as some of them are. I think it's the most charming of the three by far.
-I only have pdf versions and they're super hard to navigate.
-no skill system
2) Swords & Wizardry: "White Box"
-It's just so darn simple and clean.
-Includes ascending AC so you can use whatever you like.
-I'm iffy on the S&W:WB interpretation of the demihuman classes.
-It's just too simple at times and seems void of any flavour.
3) Lamentations of the Flame Princess: Weird Fantasy Roleplaying
-The inventory system.
-The Specialist class and the skill system.
-I'm really really not fond of the spell lists, I'm much rather use the ones in B/X or White Box.
-As much as I like some of the modernisations, I think they rob the game of some of the awkward charm that B/X has.
-The flavour of LotFP is great, but it's not really in the system, so it's not actually a pro for the game, I can use the LotFP flavour in any other game easily.
Decisions, decisions, decisions. Right now I'm thinking I'll probably go with B/X, but incorporate the LotFP inventory rules (easy) and perhaps the Skills (harder). Maybe a mix of both. I'll have to do some hacking work.