FWIW, I've always found nim's variant syntax a bit complicated. Maybe the reason is just that I am not used to the syntax because it is not ML-like, but it seems a bit too verbose to me. In the end I find that I never use them, even in cases where it might be a good solution.
I wish there was a more concise, built-in syntax to create basic sum times / unions. Maybe something like ElegantBeef's sumtypes or alaviss' union libraries.