Well, if you talk about joe repaints in the Action Force line, I use Red Laser as a Cobra affliated mercenary. I'm toying with the idea of using the first series Soldier Force figure that looks like Iron Klaw from G.I Joe Extreme as Iron Klaw and his Skar troopers (the black uniform version as iron klaw and the green version as the troopers). I've put together an unamed mercenary/covert ops guys using various parts of the Hot Toys colonial marines figures. Otherwise I do customs utilizing the headsculpts from other lines and put them on joe bodies since the original line figures lack articulation or the military look, primarily from Chap Mei and Lanard's WOW girls but also did 2 using the voltron Princess Allura head.
Of course if you talk about vehicles, it sounds heretical but I tend to largely favor Chap Mei and BBI vehicles over joes most times.