So I got to a point where I really need to declutter my vault and hoarding gallery. Would you recomment selling everything or fragment it?

I mean the Crystal shop barely stocks up but when it does we always talk about really cool stuff

I would recommend waiting until you have a GA, or if you have a one week one stored away then use it. Dump everything in your shop that you want to get rid of, autoprice, sort by price then dump out into your inventory everything under X value and toss it at the fragmentizer. Then you get the best of both worlds.

sell it

I usually put everything in my shop, price it up, and then search for anything which is worth less than 2000sP, remove them and throw them into the fragmentizer.