I've always defaulted to Slideshare for hosting slides from presentations that I've given, but it's become more and more crap-infested. The UI is messy, and the UX sucks - for example, I want to download a slide deck, I most definitely 100% am not interested in "clipping" it...even if you ask me every. damn. time:
Looking around it seems the other popular option is Speakerdeck. The UI is clean and simple, and I as both a user and uploader I feel like I'm there to read and share slides rather than be monetised as an eyeball on the site.
I'm still in the process of uploading all my past presentations, but you can see what's there so far here at https://speakerdeck.com/rmoff.