I always liked the MEC for their infantry weapons. While I never cared for them before 1.0, the Hamas have become quite interesting for me lately, I just enjoy the SMG. Other than that, Germans for their fancy weapons.
To a lesser degree, I like all irregular factions. I've always been an infantry guy, and I prefer short-range weapons, so Milita can be quite fun, for example. Never cared for AR-15s, so the US factions are sort of meh.
