I think Dale and RoleReversal summed up the majority of my opinion, other than, it is kind of like asking which is the best OS; MAC, Linux or Windows? You are gonna get so many answers it is rediculous. In most cases, he who throws the most money at promoting/advertising their product wins, which Cisco has done a great job at.
I can give you one product that I have not had much luck with...Linksys, which is put out by Cisco. For their high-end stuff to work pretty good most of the time, they sure as hell can't get the home market down, of course, that's my opinion and the experience I have had with several Linksys routers.
To the OP, remember, don't put so much faith in one product. One weak link can break the whole chain. As RoleReversal pointed out, Cisco consistently has its share of vulnerabilities, which does not necessarily make it a bad product. But, having other solutions in place is a wise choice.