There really is no comparison between a Pentax LTD lens and a Canon consumer grade prime. I took a million very good shots with my Canon EF50/1.8, but honestly these two are apples and oranges. Though, I do think the EF 50 will work better on a Canon body than the LTD will if you want to use it for photography.😉
That was a Mk I lens too, I am an old school EOS user.