Don't know the 50-135 until yet... but I had a copy of this 2,8/60-120 Tokina ATX, interresting alas not up to the Nikon Serie E 3,5/75-150 quality.
Tokina: too long minimal distance (1,20m) solidly built, better than Nikon Serie E in this case.
But colors were not up to Nikon standards, cold, bluish, softness and not good against the light (halos).
For me, the 75-150 series E is a good allrounder, with an interesting short minimum distance (1m) and very good close-ups with 3T and 4T Nikon achromatic diopters (also with Leica Elpros VIa and VIb, but these are not multicoated...but easier to find than the Nikons).
Ended up solding my Tokina, I rather buy another Nikkor or Nikon Serie E !