I've always used Leupold scope on my rifles until this year. Specifically the 3.5-10X40 model.
This year I'm using a Zeiss Conquest 3.5-10X44.
So far I've only found ONE thing I don't like better about the Zeiss scope.
The Zeiss scopes are VERY bright in low light, but I've found the reciticle is harder to see. It has a larger "thin" part of the crosshair towards the center than the duplex recticle on the Leupold models.
For precision target shooting I like it better....but I've taken it out late in the evenings and I can't see the thinner center section of the crosshair for shooting. It seems to dissapear especially when I was aiming at a dark brown hog last week.
With the upper level of your scope budget at $600, you have some VERY nice scopes to choose from. The Zeiss Conquest line will fit your budget and so will the Leupold Vari-X III models.
If I was hunting more open areas like fields or prarie areas or where longer shots were the norm I would stick with the Zeiss model. Since I'm in East Texas hunting thicker wooded areas where shorter shots are the norm and things get darker faster in the evenings, I would now rather have my Leupold with it's slightly thicker duplex recticle back.
The forums here seem to have the majority of shooters preferring Zeiss over Leupold though. I think both would make you a VERY good hunting scope to use for many years to come.