I enjoyed IM3 but I recognize its flaws. Thor 2 is much more flawed though imo. Once you start examining the plot (holes) it just doesn't hold up to the standard of the rest of the MCU movies.
I've never watched a Hulk movie and I probably won't bother until they make a good one. As for "outside the box" movies like GotG and Ant Man being popular despite expectations, all that needs to be said is that good writing can make anything likeable and successful.