i usually start at siegebreaker quest
tele to keep level 1 wp, go straight to keep level 2 and clear it till i hit ghoms room (empty)
tele to rakkis crossing wp and go to siegebreaker.
make my way through the towers and craters.
Is this the best farm route for act 3?
But when you leave the starting area with siegebreaker quest on into "The arreat gate" at the end of the rampart there can be 1 of 2 dungeons... "The Barracks" or "Fortified Bunker" i usually restart the match until i get the Fortified Bunker and start with that, you have like 3 to 4 champion packs on lvl 1 and 1 to 2 champion packs including a guaranteed splendid chest on lvl 2, apart from that pretty much what you are already doing ;)
Edit: Oh and at rakkis crossing i look for "The Underbridge" if it's there i clear that one too ;)