I have done The Thrill as always as first one. Regarding 50m gold streak I did not find it very easy and since I have Crusader as main and I have all items for another sets, complete GR55 with another sets was pretty easy on first try.
Then I rolled barb, transfer few of the items mostly rings and amulet and earthquake set was done also on the first try. I had small problems with HOTA build, but it took 2 hours of farming and then I have done it also. If you create second character with same primary attribute, you will use most of the items for start and then paragon helps a lot.
I think that three easiest conquests are :
50m gold streak
GR45 without set
55GR with 6 different sets.