Where to go from completing campaign?

My partner and I just got going on our second characters, we completed the campaign on WT1 to blow through it and get to expeditions.

Problem with this is we are level 26 now (not the 30 we probably should be to start expeditions) and we are wondering what the best way is going to be to get ourselves to 30 so we can start farming loot / expeditions reliably?

We have gone back to some of the suggested earlier missions known for xp farms but we get maybe 1.5 to 2k a completion which is going to take stupidly long for us to get to 30, and is just going to tire us out repeating the same boss over and over gets old fast.

Whats the best way for us to get our levels up faster without taking hours to farm?