Hmm, only one manufacturer? Which, revolver or auto? Or do you mean only one make for either?
If one for each, I love my CZ so I'd have to say CZ for autos (though there are better, and worse, makers) simply so I could keep my CZ 75B and S&W for revolvers so I could keep my S&W 65LS, 586, M19 and get more S&W revolvers in the future. There are other good makers of autos out there but I don't want to part w/ my 75- it has a great trigger (I know, not all CZs do, but mine does- it is even better than my best friend's 85Combat, the one that is supposed to have an improved trigger, and he has done some trigger work on his), it is reliable, it is accurate. I love that gun. For me I do like Taurus revolvers (they are an incredible value) but nothing has the class plus functionality of a good used S&W wheelgun.
If you mean one for either I'd go S&W. I could keep my S&W revolvers and they do make some nice autos too (I'd have to get a 3913 and/or 908 right away). Plus, to make it a complete "no brainer" they now make 1911s. Only one make, and there is a manufacturer that makes both 1911s AND revolvers plus some nice DA/SA autos. No question, make mine S&W.