depends how you would like to play, how much time and/or money youre willing to spend on the game, and if you want common flavor of the month combos.
just starting and dont care about endgame? try mage/priest, mages are good for a long while, especially during low/mid levels. with the priest side you can heal yourself. knight/warrior is tanky with decent damage. anything/priest or anything/druid is decent early on because of the heals.
if you care about end endgame, the highest instance out now is ran by scouts. mages dont really have a place there. sure they can do it, but an almost perfect mage will be outdamaged by an average scout. scouts currently have the highest damage in boss fights. are they going to nerf them? who knows. scout/warden /rogue or /warrior are probably the highest damage scout combos.
rogue/knight is pretty good. good damage, option to tank endgame, but they dont have the aoe to hold large groups like a knight primary, less defense, more dodge. warrior/knight has more defense and life than an r/k usually, but both are good. scout/knight can tank if theyre built good and if there isnt much need for a real tank because everyones overgeared for that area.
//tl;dr?
scout and rogue/knight are good, and im not sure how far you went with them. there are different roles in a party and you can easily find 1 or 2 of the best combinations for that role if you look on the rom forums.