Bueng Kan and Nakhon Nayok would fit the enjoyed them but do not plan on going back.
The province of Nong Bua Lam Phu, I can not say I really enjoyed the first time and have no plans of going there again.
There are a number of provinces similar to Amnat Chareon and Maha Sarakham that I would not say I enjoyed but I know I will transit in the future to get somewhere else.
I still have a number of provinces I have not visited so my list is not complete. I also may learn of a place or event I missed in one of these provinces and decide to return.