Move the old .kodi profile to .kodi backup and start over. Judging from the changelog there have been a lot of changes to the media libraries so we might as well start afresh.
On Ubuntu you will need to apt-get dist-upgrade to get Kodi 17 rather than just upgrade because of new dependencies. This is assuming you’re working with the official PPA.
On Ubuntu you’ll need to manually install kodi-inputstream-adaptive (as a package using apt-get, not an addon in Kodi) in order for DASH to work. DASH is used by the YouTube addon to allow for greater and more variable streaming quality.
On Ubuntu you may have to manually install kodi-peripheral-joystick (again as a package) to get your controller working.
Installing SuperRepo v17 allows for browsing the packages but either something’s amiss with the repository or I’m being a dumbass. Lots of ERROR: CCurlFile::Stat – Failed: Couldn’t connect to server(7) in the kodi.log, though. To download a package manually from Superrepo.org, e.g. Steam, click the button that displays the number of downloads, the click SuperRepo location and save the zip file. Then choose Install from zip file in the Add-on browser (the cardboard box icon in the Add-ons menu). Or maybe you can just add the Jarvis repo instead of Krypton and get away with it?
Favouriting an add-on directly in the Add-ons menu is not possible as the option does not appear in the context menu. Go to the My add-ons submenu and find the add-on in the proper category, e.g. Program add-ons for Steam, Video add-ons for YouTube etc. Context-clicking it there will provide the option to favourite it.