I used the FDn 50mm F1.4 for more than 20 years and it was a better lens than I'm a photographer.
I never understood the equation. Forensically exhausting detail has never been synonymous with creative photography. Aerial surveillance, possibly and medical imaging certainly but the creation of a visceral impression on a viewer, not so much, especially in 35mm. The FDn 50mm 1.4 is pretty sharp except wide open - which is only to be expected - but can suffer from focus shift between f2.8 and f4. I'm not the only person to observe this phenomenon. For these reasons I tend to use it for video, where wide open softness is appreciated, or on a mirrorless camera where shift can be observed through the viewfinder and remedied.
Many of the world's finest photographs were taken on lenses that were objectively bad by contemporary standards. What they had going for them was a great eye through the viewfinder (which was often worse than the lens optics!). The Canon 50mm is the only f1.4 SLR lens I can recall that was sold, or perhaps promoted, as a standard kit lens from the shop. I've never known so many cameras fitted with this wide aperture 50 as A-Series Canons.
I rather like the rendering of the 1.8, though I've heard conflicting evidence as to whether it was multi-coated. If it was single coated, it's a quality shared with another of my favourite lenses, the Yashica DSB range. I own ML and DSB glass and the latter has a classic quality not unlike early pre-AI Nikkors, or indeed old Leica lenses. The problem with CY lenses is finding a reliable body to fit them on. For feel and appearance, breech mount FD lenses are up with the best, though the later plastic versions may have the edge optically.