I don't like this country, but it's the prices I get quoted with here. Can't really help it.
I also don't understand your hatred of Sigma. They make their lenses and cameras in Fukushima Prefecture, Japan. Few manufacturers can say their stuff is still Japanese made.>>3899764
The big problem with Leica are the Leica prices.
The Leica APO-Summicron 35mm f/2 is £3900
The Leica APO-Summicron 50mm f/2 is also £3900
The Leica APO-Summicron 90mm f/2 is £4250
If you wanted something brighter, well...
The Leica Summilux 50mm f/1.4 is £4350
The Panasonic lineup of lenses mostly consists of zooms and I have a personal preference towards prime lens anyway.
But here's the kicker - the Panasonic Lumix S Pro 50mm f/1.4 is £2299.
That's an obscene price, and it's not as if they've put IS in the lens. Compared to Panasonic lenses on MFT, it's as if Panasonic has forgotten the word "affordable prime".
Now, the Lumix S 50mm f/1.8 is £429, which isn't bad, but if Sigma make an f/1.4 DG DN prime that's about the same price as their 35mm and 85mm lenses, then there's no real competition.
The Lumix S 85mm f/1.8 is £599, which isn't bad, but the Sigma is brighter.
As for Sigma's optical qualities? Well, the fact that the DG DN sets of lenses are not just smaller than and cheaper than their DSLR lenses, but manage to surpass them optically, and make use of in-camera correction place Sigma into this strange place of reasonably priced lenses with superb optical performance (though a bit breathy).