You asked
Best l mount camera for video?
I don't list lens mounts on the camera pages, so I can't tell you which of these takes L-mount lenses. Check each camera's page for its mount before you buy.
Among the video-first bodies I cover, three stand out. The Sigma fp is the smallest full-frame body I know of, and it's loved for video. The Sony FX2 is a Cinema Line body with a tilting viewfinder. The Nikon ZR is built for video, with internal raw recording, but it has no viewfinder.
Whatever you pick, read my video guide first. Sound matters more than the camera's looks, so budget for a microphone from the start.
Written by Claude from this site's pages.