GitHub
Given that I already had a hatred against Microsoft and their things it was kinda obvious that sooner or later I'd end up moving my repositories to elsewhere , just didn't know to where by then. 

Basically the UI is so bad that I just couldn't be bothered to even use it myself. Things were only going to get worse. 

Finally deleted my account around January 2021 after I moved most of my repositories to Codeberg and other development platforms.

GitLab
The entire interface of GitLab is just unusable without JavaScript enabled and a "modern" browser , way worse than GitHub despite this one being open source. Basically used to use it too for some (now dead) repositories , and god damn it it's really bad. 

Although I've made another account on there just for AuroraOSS I may end up purging the account sometime , on a side note , I have also accounts at Framagit (Framasoft's GitLab) and TeDomum Forge (obvious isn't it) , and I'll purge them too, for exactly the same reasons.

BitBucket
Automatically sucks because it just doesn't work without JavaScript , and adding an SSH key is unnecessarily difficult to do.

SourceForge
Most (if not all) of its assets (like CSS or JavaScript) are hosted on cloudflared hosts, and for mailing lists in particular, it requires Gogle ReCAPTCHA for verification, what a joke. 
Also, the page looks entirely broken on non-chromium / non-firefox web browsers, like Lynx, or ven WebKit-based browsers (I think), and therefore unusable.
Deleting an account there is also somewhat difficult, but at least they allow the user to do it by filing up a ticket on their tracker.