50 f1.4 IS (L) prising ~ 600 - 1000$
It is shame for Canon, but from my point of view where is no perfect 50 mm lens currently in its optics line.
50 1.8 II is too cheap and plastic
50 1.4 is not optically perfect and has known mechanical issue
50 1.2 L is too expensive and quite soft until well stopped down
I know that company is very proud for its reputation of best reportage brand, but I hope it has enough resources to provide also perfect solution for most popular fix-focals between upgrades of next "big white pipe" ).
The lens should be optically and mechanically perfect! Also due to Canon doesn't provide sensor stabilisation IS is very desirable (for almost every new lens). I also agree to pay extra for weather sealing and Luxury quality.
The best Canon 50mm EF lens IMHO is the 50mm f/1.8 Mk I. Tiny size, reasonable build and good optically. However no longer available new of course. Thankfully some good copies still exist ;-)
5Dmk3, 5Dmk2, Sony NEX-6 | SY14mm f/2.8, Ʃ20mm f/1.8, 35mm f/2, Ʃ35mm f/1.4A, 50mm f/1.8 I, Ʃ50mm f/1.4 EX, 100mm f/2.8L Macro, 17-40L, 24-105L, 70-200 f/2.8L IS II, 1.4x II, 70-300L, 100-400L | E-mount: 16-50 OSS, Ʃ30mm f/2.8 EX DN, 55-210 OSS | 2x FT-QL, AE-1 Program, some FD(n) & FL primes