Agreed on the Tak' 28mm f/3.5. Very, very sharp even wide open, wonderfully saturated colours and contrast straight from the sensor.
I love mine and I use it as my 'kit' lens as it has a focal length of just under 45mm on a 1.6 crop sensor. Made even better by me getting it for less than their average value due to the seller not really listing it correctly.
If you want something relatively wide
and fast, you could try and source a Tak' 35mm f/2. They're quite rare though, and due to a radiated element is prone to yellowing. But that's reversible with a UV bath.
I also own a S-M-C 200mm f/4 which is sharp wide open, 'tak' (
) sharp at f/8, and maybe wider than that, not had chance to test it thoroughly. It can be a bit too long for some people though, I'd love to try out a 105 2.8.
Here's the first shot I took with the 200mm at f/8 to test sharpness and bokeh. No PP except a resize.