You asked
Canon rf 45mm f 1 2 stm vs laowa argus 45mm f 0 95 ff?
Both are 45mm primes for full frame, so the choice comes down to how you like to work.
The Canon RF 45mm f/1.2 STM is the easier lens to live with. It autofocuses, weighs about 350 g, and is made for Canon RF cameras. Its f/1.2 gives plenty of background blur and low-light speed, so if you shoot Canon full frame, it's the sensible pick.
The Laowa Argus 45mm f/0.95 FF is brighter on paper, but it's manual focus only. It fits Sony E, Nikon Z and Canon RF mounts, so it suits people who switch brands or who enjoy slow, deliberate focusing. The Laowa page lists its aperture as both f/0.95 and f/0.9, so check the spec before you buy.
If you want autofocus, start with the Canon. If you're happy focusing by hand, the Laowa is the more unusual lens. For general advice on building a lens kit, see Lenses.
Written by Claude from this site's pages.