I'm currently taking a vit E supplement, (but then i've been a bit of a supplement junkie for most of my life!). It's a base of 400iu alpha tocopherol, but has mixed tocopherols in it too. I'm mainly on it again because, i take quite a bit of omega 3, but also i read about it somewhere helping with rheumatoid arthritis which i get in my thumb joint. My main supplement for that though is high dose vit D, which seems to keep things under control at the dose of 15k iu i'm on.
Curcumin, i've been taking various forms of it (Meriva, C3 etc) on and off for a while now. Never noticed anything dramatic from it with regards to joint pain, but i know the science backs it up and it's generally considered 'healthy' so i keep adding it in.
As to boswellia, that's one i keep reading about and meaning to try - have you noticed much benefit from it yourself?
I'm also looking into black seed oil - i saw a short video by Dr Eric Berg on it. He reckons it's more powerful than ibuprofen as an anti inflammatory, but then his videos do seem a bit click-baity (like most influencers i guess).