I have had good luck with Burris and Alpen. They are both decent. The Alpen has a finer reticle. The Burris is built stronger. I would rate them in order of best first with some of yours that I have experience with: Leopold, Vortex, Burris, Nikon, Alpen, Bushnell, Simmons. Since you have the first 2 I will recommend
http://burrisoptics.com