I like the 55mm C, the 80mm C, the 80mm f/1.9, and the 210mm f/4 for sure. If the 300mm f/5.6 is as good as the 200, and if the 45mm is as good as the 55mm, I know I will like them as well. They are next on the list for sure.
I like the WLF, but I always prefer to use a prism. I sold my metered prism along with my third body, and intended to purchase a plain prism instead. I don't like all that metering junk sticking into the composition when I never use the meter anyhow. However, finding a plain prism in good shape for a good price has proven difficult.
I have a plain M645 and a 1000S. (Both bounce and ruin pictures at the top shutter speed.) I have one WLF (with sportsfinder and mask insert) between the two, a left hand grip, and a motor drive (allows right hand firing and left hand focusing, which is the main reason I wanted to get it). For lenses, I have the 55, the regular 80, and the fast 80. I have a 210 that is on semi-permanent loan, though I do want to get my own copy. I got lucky and also have a nice metal case for it all and four film inserts with cases (two 220 and two 120).
So, the "wants" for the system for me are:
standard prism (or two)
my own copy of the 210mm
45mm
300mm