You are looking for a "normal" lens...
On crop camera, that's a 30mm and the Sigma 30/1.4 is the only prime available at that focal length.
Both 35mm and 40mm are slightly "long normal"... a little more telephoto than usual for a normal lens.
The Canon 28/1.8 is slightly "wide normal".... just a little wider than usual for a normal lens. This is the lens I use and prefer. It's one of the most compact, reasonably fast EF/USM lenses, even with it's matched lens hood. I also like that this lens is usable on both crop and full frame. On full frame wide open it's a little soft in the corners, but on a crop camera you don't see this at all and it's a nice sharp lens. Because it's a USM lens, it's as fast, quiet and accurate focusing (probably even better than your 50/1.4).
Since you already have a 50/1.4 ( a nice "short portrait tele" on a crop camera), I'd suggest either a 28 or 30mm to better complement it than a 35 or 40mm would.
The Tokina 35/2.8 is a macro lens and will focus within a couple inches, to 1:1 magnification. It's a pretty short focal length to shoot macro, puts you quite close to the subject. It's the sort of macro that might be used for copy work or small products in a studio... probably would be fairly challenging to use in the field. I'd normally recommend a 60mm to 105mm macro lens for general, walk-around shooting purposes. These are a reasonable compromise of working distance vs handholdability. I used to recommend 90 to 105mm, but the Canon EF-S 60/2.8 and Tamron SP 60/2.0 Di II macros are excellent, compact alternatives for use on crop cameras (both are "crop only").
You might want to replace your 50mm with one of these 60mm macro lenses (the f2.0 Tamron might be preferable for dual-purpose use, such as portraiture, but it's likely slower focusing than the Canon 60mm)... or add a Sigma 75/2.8, Tamron 90/2.8, Tokina 100/2.8, Canon 100/2.8, Canon 100/2.L IS, or Sigma 105/2.8 OS to complement it.
Or you could simply add some macro extension tubes to your kit, useful to make any non-macro lens closer focusing. The Kenko are high quality and a good value. The ProOptic (Zeikos, Bower, Vivitar, etc.) and Opteka are a couple cheaper alternatives. (Stay clear of the really cheap, under $25 tube sets... they don't have electronic contacts, which means you lose autofocus and direct control over the aperture, making them a pain in the arse to shoot with.)
This rose bud was shot with Canon EF 50/1.4 on a Kenko or Canon extension tube (20 or 25mm, I forget which), on a crop camera....
It was deliberately shot at a large aperture, which tends to soften the corners and add some vignetting with this particular lens on an extension tube. Stopping the lens down reduces both these effects.