Hello,
Here are the 5 bosses I'll be focused on grinding for my upcoming hardcore ironman....
While almost any boss is grindable at a mid level, these are the ones that I think are the most valuable. Not only will you get some nice collection logs, you should be able to get some combat achievement points.
I tried to keep in mind gear and equipment requirements when going into the bosses, while there probably are some harder bosses you could grind I think these will be comfortable.
Let me know if you think I missed any good ones, thanks!