Some of the best campaigns are at PMC Tactical, specifically the PMC Baltic dynamic campaign, and PMC Fury. PMC Tactical
btw I'm currently playing the Baltic campaign using the FFSX2007 2.5.5 mod and the immersion and battlefield combat coupled with the excellent scripting and campaign engine that PMC put together makes for a highly engrossing and fluid battlefield actions, certainly the best campaign I ever played on OFP, for that matter any combat FPS. Please note that the Baltic campaign requires the COC addons which allow for multiple group command and control. Check it out, it's awesome.