If you are choosing between a Sig P226, a CZ 75, and a Beretta 92SF, you are looking at 3 different pistols, all of which are of equal comparable quality, with different features. CZ's offer a steel frame and a frame safety; Berettas and Sigs have aluminum frames only, Berettas have the safety on the slide, and Sigs only have decockers. Depending on your preferences, that could elevate one gun above the others... or it may not.
Anyone, particularly a guy trying to sell you something and who should be knowledgeable about the weapons, who tells you otherwise, is lying or ignorant, and should not be trusted.
I fully expect you could post this question on both Sig and Beretta forums, and they'd tell you the same thing. They might tell you why they prefer a particular design over the others, but I don't think anyone would objectively say that CZ's aren't good guns.