What exactly would you like to use the lens for, and what are your requirements?
Over the last few years I've tested well over 30 50 mm AF and MF lenses compatible with or adapted for Canon, and essentially it depends a lot on the intended use for your camera. How important do you find is (real) USM for example?
50 mm lenses with AF I would recommend, and in this order, are:
1. Canon EF 50 F/1.2L
2. Sigma 50 F/1.4
3. Canon 50 F.1.8 Mk I, 50 F/1.8 Mk II, or 50 F/2.5 Compact Macro
4. Canon 50 F/1.4
Personally, I shoot a lot of low light, fairly close-up portraits, group portraits and landscapes with a 50 mm, which means that for me with my perfectly calibrated 50L, that is my goto lens, and it is mounted by default on my 5D II. The focus shift issues this lens used to have are a little exaggerated, especially with current production runs. Despite comments to the contrary, this lens is sharp wide open, but the DoF plane is very thin, and under certain conditions it may show a little halation at the widest apertures (causing a dreamy effect). Colour rendition and contrast are very nice indeed, and this is a lens that is capable of creating great "3D" pop. It is also great at smaller apertures. Bokeh is out of this world, and it is not only good at bokeh behind the DoF plane, but also in front of the DoF plane, which essentially is something that from an optical POV is contradictory, and therefore even more impressive.
The Sigma 50 is not a bad lens, but you have to be aware that it has a little focus shift, doesn't necessarily focus equally well at shorter distances as it does at longer ones, and although it is quite sharp up to F/2, sharpness decreases at F/2.8 and F/4 a little, after which it increases again. Bokeh is good. Personally I don't particularly like the slight yellow cast this lens gives to images. That is a matter of taste however, and a calibration of this lens may overcome any problems encountered, if indeed you do.
The 50 F/1.8 Mk I and Mk II are optically the same, the main differences being build quality and AF mechanism. The Mk I has a metal bayonet, a proper focusing ring and focusing scale, and the older AF motor which is a bit noisy, more so than the micromotor used in the Mk II. The build quality of the Mk I is quite high, actually. This lens is usable (good) at F/1.8, and gets sharp at F/2. Bokeh is ok-ish, unless you get specular highlights when stopped down when you are not a fan of pentagonal reflection shapes. AF is a little slow, but accurate from my findings, although one needs to know how to handle AF when using this lens, i.e., always focus on something with a good contrast transition, as we used to do in the film days with MF, especially in low light or low contrast conditions.
The 50 F/2.5 CM is an excellent lens, sharp from wide open, and it has very good bokeh indeed. Just not very fast, and AF is also slow, plus the AF engines sounds almost like the lens has an in-built angry wasp for an AF engine. If you can live with the sound and relatively narrow maximum aperture, it comes very highly recommended. Optically it is a gem.
The 50 F/1.4 is an old design 50 mm, which behaves more or less like all old designs, namely soso wide open up to F/2.8, where it suddenly becomes excellent. The difference between it and older MF lenses is that it has AF. I also found it not to be very reliable when focusing close, especially in low light or low contrast conditions. Personally, If I wanted an F/2.8 lens, I'd rather go for the 50 CM <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
If you'd like to go MF, with adapter, I'd suggest you go for any of the 50 mm F/1.7 to F/2 models out there, except for the Pentacon models. Of course, Minolta lenses won't fit, but a permanently adapted 58 F/1.2 MC Rokkor would certainly be something to consider. It would probably cost about as much as the Sigma 50 F/1.4, and be MF only, but it is a very good lens, and goes to F/1.2 <img src='http://forum.photozone.de/public/style_emoticons/<#EMO_DIR#>/biggrin.gif' class='bbc_emoticon' alt='
' />. The reason for not generally using any faster 50 mm MF lenses, is because the lenses available are all older designs Ã la Canon 50 F/1.4, and show the same problem: soso up to F/2.8, and suddenly excellent from thereon. The only exception I have found so far is the Zuiko 50 F/1.4, which is good at F/2, but doesn't get much better, and is never as good as the other fast MF 50s. A newer slower MF 50 is the Zeiss ZE 50 F/2 Macro, but that is rather expensive for an MF lens, and you have to like the Zeiss rendering. Personally, I don't, but that is a matter of taste.
As to 35 mm lenses, I am not a personal fan of them, but that is because I don't gel with the FL. I prefer 24-28 mm and 40 -50 mm. Options you could look at are 28 mm Canon lenses as well in this context, I guess. The 35 F/2 is considered to be a very good lens, as sharp as the 35, just slightly different in colour rendition. 28 mm wise there is a Sigma F/1.8, which I don't know so won't say anything about, but there also is the Canon 28 F/1.8 and F/2.8. The F/2.8 is a lens from the same generation as the 35 F/2, and for the money it is an excellent lens. The 28 F/1.8 is the little sibling of the 85 F/1.8 and 100 F/2, and has USM. The specimen I had was very, very good, extremely usable wide open, and very sharp at F/2. I regretted having to sell it, but by then I had the 24L, which was slightly better for low light photography.
This brings me to the 24 mm options you may want to consider. 24 mm on APS-C is a short standard lens, and a proper WA on FF. I like this particular FL (but I do like 28 mm too, actually), and a 24L Mk I may be an option to consider. They go for 800-900 euros lately, with a bit of luck for a little less. A few years ago this was the lens to beat in its FL - it was (still is) a world class lens, even though there are a few slightly better ones these days. A cheaper option is the 24 F/2.8, same generation again as 35 F/2, but a hidden gem nonetheless, and also worth considering.
This brings us back to what you would like to use this lens for. If you are looking for a short (portrait and landscape) tele on APS-C, and a normal lens on FF, by all means, go for a 50 mm lens. If you are looking for a slightly longish standard lens on APS-C, and a borderline WA on FF. I guess the 35 F/2 is the way to go. 28 mm is a standard lens on APS-C, and proper WA on FF, allowing for group portraits f.e., and 24 mm is a slightly shorter WA on FF, borderline UWA, and a short standard lens on APS-C.
Personally, I preferred 24 mm and 28 mm as a short standard lens on APS-C over a 35 mm, basically because I just don't "get" 35 mm on APS-C, and the same is true on FF. I've owned several 35 mm lenses in the past, and the last one I tried was a 35L a few years ago, but it just doesn't work for me. On FF, to me it is too short to be a standard lens, and too long to be a WA, and on APS-C it is too long to be a standard lens, and too short to be a short tele. That is a very personal thing, however, and something to try out for sure - just try setting a zoom to either of these FLs for a while, to see which you prefer yourself.
BTW, "(color) dynamic range" doesn't exist, and I guess what you really mean is colour rendition and (micro) contrast. Any of the abovementioned lenses will do well in this regard, but generally the more expensive ones will do better, IMO anyway. To a degree, deeper colour/more saturated colour and (micro) contrast go hand in hand, although overall colour rendition can also be influenced by lens coatings. Personally, I like Canon L rendition in this regard, but others do like the way Sigma lenses render, and others again prefer Zeiss.
HTH, kind regards, Wim