I have owned or do own those lenses you mention on both a crop and a FF body. I really think the 28 1.8 is one of the worst QC'd Canon primes out there. MOST have horrible corners albeit sharp centers. The variety of reviews is all over the place.If you are on a budget and want a 'normal' prime for a 1.6 crop then you should consider the 35 f/2. It has great color, pretty good bokeh and is small and inexpensive. It's AF is might slow and buzzy however.
If you can afford it the 28 2.8 IS is a fantastic lens. Excelling at everything except stop motion in low light.
The 40 is a strange FL on a crop but is amazing for the money on a FF. Great street prime, group portrait, stealth mode lens and a lens cap you can shoot with.
It's AF speed is not unlike the 50 1.4 but it hunts in a different manner. Not true ring usm fast but much speedier than the 35 f/2.
If you are staying with crops and have no inkling to go FF in the near future you might consider a 17-55. Sell the 24-70. It's a nice lens but a 900+gram brick. The 17-55 might solve your 'normal' focal length search and I betcha you'll carry it way more often than the 24-70.