I have owned both the Canon 50mm f/1.8 and f/1.4 lens. I must say there is a dramatic difference between the two, a greater one than between the 1.4 and 1.2
I shot with both on a 1.6 crop for many years and found my ability to adjust to the equating 80mm focal length to be fine. Difficult at times, but it worked.
With the 1.6 crop in mind, I would also suggest a Sigma 30mm 1.4
However, I feel (regardless of the camera body) the 50mm 1.4 is a great lens for the money. I shoot primarily with a 5D mk ll and the 50mm 1.4 is mounded 95% of the time.
As your first prime, 30mm is a great start with 1.6 factor in mind. Possibly pair with a zoom, and you'll be well off