Hi,
I guess it will depend on your type of photo ... Landscape or sports ...
Speaking of my own experience, just swapped from 40D (5 years) to 7DII end of last November, and i'm loving it (3k pics): coupled with 70-200 2.8 IS II, it makes a great combo ... I quite often shoot 800 and up to 3200 ISO (inside shots or for using the 2x extender) and results are quite good compared to the unusable soup of 40D at that level.
What i especially like on 7DII compared to 40D are the following:
- higher usable ISO and increased resolution
- 65 points with great user control to choose and compose in one touch (cf. below point, for sports but also macro with 100 2.8 L Macro and 24-70 4 L in its macro position)
- super high speed and silent speed all customizable
- customization (menus, lots of buttons can be customized, easy access to autofocus options and presets, focus points, ...); lever on back joystick is pretty convenient and also customizable (use it for ISO)
=> classic settings I am getting so used to is to be able to go with a push of thumb/finger from classical one shot to AI Servo and point extension/zone setting with focus avoiding obstacles for sport with high speed, or in some other cases to finetuned focus point composition with AI Servo for Macro jewelry/fine art macro, all while looking thru the viewfinder
A few reasons i didn't want to jump to 5DIII and FF (yet):
- reach (i got a 2x ext on the 70-200)
- speed (birds, sports ... and kids!)
- my 10-22 that i love
- price (preferred to upgrade glass)
- integrated flash for quick flash fill without bulky external flash to carry/install ...
- fancy gadgets on 7DII (gps, higher customization degree ...)
For UWA, you might try the 10-22 : have a look at the forum's images, it's a lovely lens, a few people deem it close to L quality (one that i didn't want to leave to my goddaughter if changing to FF!), you just have to be careful not to get your feet in the pics !
Regarding the 40D, why don't you try to give it to your gf ? Put the 50 1.4 on it, and you will be happy of the nice portraits she takes of you

My ex had a 550D and she always wanted to get my 40D ... (now i'll give it as an upgrade to my goddaughter after she trained on my old 400D)
But on the other end if budget is not an issue with you, get 5DIII and one of the 16-35 ...