I personally prefer Pentax, and I have three of them, all Game seekers ;
a 1.75-5x20 on an 8mm mauser
a 3-9x40 on a .280 Remington
and a fixed 6x42 on a ?
I have a couple of rifles that I am undecided at this point. As far as Simmons go, I had one once and it didn't perform, when it really counted, and let a really nice 8 point buck walk @ 320 yards.
I have been with hunters in the field with Leupolds that failed, although they have a great warranty and customer service, they cost a hunter his hunt, so I won't own one of those either.
But there are plenty of other quality brands out there, Weaver (which I own), Nikon, Burris etc.... Good Luck!