Git is definitely dominating the landscape. The fact that it is free software plays a big role. There are alternatives, but they are unlikely to gain much adoption. They may provide slightly better UX or marginally more comfortable flows, but it's not enough to replace Git. Not to mention, most developers don't even really care about which SCM they use.
I used ClearCase too :) And it was painful. But I don't think CVS and/or ClearCase are considered to be meaningful alternatives to Git at this day and age. I was mostly thinking about Mercurial and Fossil. They are brought up as alternatives to Git more often. That's my observation at least.
I never used CVS but the senior developer at one place mentioned about it once when I complained about subversion which we used there (this was in 2013).