The Ubuntu font for example is definitely not shitty -- it was designed at Dalton Maag and it is a considered piece of work that a lot of typographers rather like.

It's definitely rather idiosyncratic, mind you.

So I don't personally use it on Linux. I use Google's Roboto, which is close enough to Apple's later San Francisco (which shares some common heritage and some common modern touches) that I don't go insane when switching between the two!

Roboto is again a considered bit of work by a highly competent designer.

I don't have problems with either. If I did, I could use the Fira suite, which is lovely.