I have been a longtime Leupold user but have recently gone over to Nikon Monarchs 2-8 for our 416 Rigbys and the Nikon Slughunter 1.65-5 for a 500 AccRelNyati.
Why?
The eye-relief is better designed. The Nikon 2-8 has 4.0-3.8" eyerelief which is OK, but the Slughunter has 5.0"-5.0" eyerelief throughout which is wonderful for a heavykicking rifle. (Even 5" eyerelief isn't foolproof, though, as a friend of mine demonstrated when shooting the 7000 ftlb rifle.)
Eyerelief is not the main criterion, though, for a scope. A scope must have excellent clear glass, and these Nikons qualify on this score. Excellent. 95% light transmission on the Monarchs, 92% on the Slughunter.
Finally, and as important, the scope must hold together. Judging from feedback of many shooters and thousands of big bore rounds, it appears that the Nikon are considerably more sturdy than even the fabled Leupolds.
So I would say that there is a new kid on the block.