The question is too broad. What is the intended use of the scope?
This is a generic reply and does not include specialty scopes like USOptics, ACOGs or ELCAN type devices. For warranty coverage, Leupold is the best. Nightforce is a nice cost-no-object scope, but are primarily large objective lense, higher power and heavy.
For me, I prefer Leupold and if I want cheaper, I use Bausch&Lomb or Bushnell. One advantage of Leupold for mass market scopes is reticles. Leupold has many of their own, and Premier Reticles can supply just about anything else at a decent cost.