Sticking to 35mm SLRs. The Leica R lenses are in general spectacular because their size allowed the Leitz engineers to solve many problems they'd long been working on for the smaller-diameter M lines. It would be repetitive to put Leica R for each focal length but one might well do it. The Summicron R 50/2 certainly deserves standout mention, as do a slew of others. In the long lenses, from 180 up to 400, you are, according to the famed Erwin Puts, dealing with near flawless lens design, simply the best glass there is. This is most especially true of the APO 280/4 apparently. Now, on to other lenses, only ones I have known (I haven't owned all these, but I've been fortunate enough to use almost all of them):
Minolta MC Rokkor 21mm f/2.8, OM 21/2, Nikkor 20/3.5
Minolta MD Rokkor X 24/2.8; Contax 25/2.8; OM 24/2 (which I just got and developed first rolls and oh sweet!) I'm shocked how many people love the Nikkor here, I have had three and none was particularly good.
Nikon 28/2 OR 28/2.8(Ai-s only); Contax 28/2.8; OM 28/2; Canon FD 28/2
OM 35/2 and Canon FD concave 35/2 (I haven't used the Contax, alas)
Pentax SMC Tak 50/1.4; Contax Zeiss 50/1.4 Planar; Canon FD 50/1.4 SSC; OM Macro 50/2 (!!); OM Macro 50/3.5; Nikkor Ai 50/2; Nikkor AiS 50/1.2; Micro-Nikkor 55/3.5 F (pre-Ai); MD Rokkor 50/1.4 and MC Rokkor 58/1.4 (I haven't used the famed 58/1.2 but is, you know, famed.)
Rokkor MD 85/2; Contax/Zeiss 85/2.8; M42 Pentax SMC Tak 85/1.8 (!!)
MD Rokkor 100/2.5, Canon 100/2, OM 100/2, Nikkor 105/2.5 (!!)
Canon FD 135/2 (!!) (I'd love to get the Minolta 135/2 but it sells for $900-1000 these days, when it is available at all; the Canon is spectacular and can be had for $300 or a shade less.)
Nikkor AIS ED 180/2.8 (!!)
MD Rokkor 200/2 , Micro-Nikkor 200/2
Canon FD 300/2.8
You would think for the basic focal lengths you'd be best with Minolta or Pentax perhaps but the problem is their cameras. Some people love the Spotmatics and K's and the SRT's but I find them uncomfortable and un-smooth. The best of them are the Pentax MX and ME's and the Minolta XD's. But the Minolta's are not reliable. Whereas Nikons, fabulous. The OM2n and OM's in general, also fantastic. The OM lenses though are getting pricier by the minute and they were never cheap.