I've had to do LF on a budget myself, so I know how it is.
Personally, I went with 4x5. Mostly because in the U.S. there is a huge amount of used gear available. For just a couple of hundred dollars you can get a working Crown or Speed Graphic with an old Polaroid back and an old tripod. Or for a little more you can get something like an old Calumet 400 series for more movement.
Lenses are also much cheaper for 4x5, although if you want cheap you end up buying older lenses. Which is a risk.