I will refuse to work anywhere Clearcase is used for two reasons: 1) the horrors of using it are unspeakable, and 2) it is a good indicator that the company will not be a fun place to work for other reasons.
As long as we're playing the one-downsmanship game, I'd rather use Clearcase than Serena. At least if there was a big enough set of servers to run the VOB and view server functions for Clearcase so that it responded. The funky virtual file system in Clearcase does take getting used to, though.
That said (ramble here...), I've Used RCS, Clearcase, VSS, CVS, MKS, SVN, Git and Serena. I like Git best, but SVN just isn't all that bad. It works plenty well enough. Never had reason to use Mercurial yet...
I've only read of the "original" SCCS, but never seen it in the wild. Did it actually work well for its practitioners? (e.g. - RCS, for all its weaknesses, works well enough for a small project and small local, trusted, group)
Yep, the use of deprecated/inferior tools is a telltale sign that a company does decisions (or is unable to make decisions) because of legacy/politics/ignorance/other bad reason.
My alarm bells ring every time I hear a company using CVS or Perforce or something even worse.
Sometimes you just gotta suck it up, though. I have to use Perforce and Google Repo at work and it not only sucks, but is making me lose valuable coding time daily when I have to use an inferior tool to what's available out there.
It pretty incredible that in both of OP's experiences with SVN, he's persuaded the client to move across to git! That seems a pretty unusual move for a client to take on the behest of a contractor.
How they manage their code is their business. The OP needs to grow up.