"I've always hated the OS deciding it knows what I want." - Ditto and
you can look on a fresh install of Ubuntu as a canvass to build on.
The rather fussy background can be done away with to leave a plain one
and you can customize the look as much or as little as you wish... all
without needing to learn much more than where the necessary buttons
are to do it ( same as any OS and even Windows likes to move stuff
around between versions for no apparent reason ). Same with the
GUI - if you don't get on with the one that presented you can easily
switch to a different one and try that.

Personally I've found Ubuntu to do everything I need and very easy to
use plus rock solid in operation - what else is there to want in an OS


As for Photoshop - have you given 'The Gimp' a tryout ? It's laid out
in a similar fashion to Photoshop ( deliberately ) so you should be
soon familiar with the way it works. To run Photoshop you'd need to
have a virtual Windows but even that's not an onerous task with a bit
of guidance ( basically, install Virtual Box then create a Windows VM
and install a valid copy of Windows in it ). You can run this Windows
at the same time as Ubuntu so get the best of both :-)