Sorry if this is covered - I don't think so - or if I have a detail wrong, but there are several, optically different, Nikkor 28mm F/2.8's.
One is JK's AIS 8 element, focusing to 0.2m, the others can have 5, or 6, or 7 element.
See http://www.photosynthesis.co.nz/nikon/serialno.html though I think kI have one which doesn't fit their demarcations, which does happen.
The MF "E" , though AIS fitting, is 5 element.
The "better" 28mm, yes is definitely better.
Yes Teamspeed, taking a Canon lens off while stopped down seems to be perfectly OK, though I've never heard Canon recommend it, have you? I've tried an MP-E reversed, but not "tested" it, beyond proving it works. It's one way to get an MPE working on a D810 . And while it occurs to me, if you want to reverse a Nikkor G lens, use a Nikon- Canon adapter ring, which gives you a lever for the aperture peg, which looks better than a matchstick jammed in.
Another lens along John's line of thought - or group of them - is the Sigma 24mm primes. There's a MF f/2.8 which focuses down to 1:4, and doesn't cost much - GET ONE! It should be under $100. There are wider aperture and AF Sigmas which focus even closer for a lot more $$$. But at about f/8 they're no better (according to a Sigma rep I asked). They're certainly up to "very good" level. A nice feature of the manual f/2.8 is that the slimmest of the Nikon K macro rings is shorter than the focus throw (6mm, obviously), so there's NO gap.
I haven't used it reversed, but I'd expect it to be at least OK, because it's working at something near its designed focus distances ("conjugates").
It varies, but reversed primes often work better on a longer prime, with both focused at infinity, than on tubes. The corners are where it usually notices. Obviously, on a 100 macro you get ~ 1:4..
And, obviously a right-way close-focus 24mm on full frame is that bit more punchy for perspective than a 28mm.
That reminds, me, I must sell my Nikkor 28 AF - I never use it.
Shall I describe it as reversible for photmucrography?
Does everyone know that almost any kit "standard zoom " makes a remarkable ( assuming you have one, so it's free) macro lens, reversed? A Nikon 35-70, F/3.3-4.5 is ok, as is a Canon 18-55EFS, or a Pentax 35-80 f4-5.6. Some vignette depending on the sensor, but they all let you go close. I tried a couple of wide-range zooms reversed - dramatic, and quite bad.
There's an interesting article about the Pentax, if I can find it.
Edit - here it is: