Having used a note 3 for over a year now I can say I hate the Samsung overlay. It's bloated, slows down and has a gazillion things I don't need or want. Much prefer stock android myself. Previous phone was a nexus 4 and I have a generic chinese tablet that's stock. Work bought me an iphone 6 which is still sat in its box as I can bring myself to switch....
Lol, well technically I bought it myself. We needed an iOS platform to create some process documentation. I suggested a refurbished ipad mini as it was the cheapest. Got told the device should be more closer to what our users have amd to go buy an iphone6 and that after my documentation is done I should use it.... Can't sell it. Thinking to stick my us work sim into it as I'm current using a really crummy cheap as lg which crashes even 45 mins. Plus our mdm solution supports the ios platform much better.
OK, so is it possible to for example take Samsung S6 and reinstall the OS with some pure, non-samsung version? Without those useless apps etc?
Yup, however requires messing with the bootloader which can invalidate the warranty. Check out the forums at xda developers for specific roms and how too's
OnePlus is still invite only at last check. And he would need to pay for the entire phone up front which may not be a option. Its very much possible to stick stock andriod on the phone. But not every phone comes with a unlocked boot loader to allow this to happen. You need to do your research on that to see which does.
OnePlus 2 is invite, The original is available, 64GB for £219, And yes, your right, you would need to buy the phone up front. Sam