I think it really depends on what you are looking for. Weight, size, capacity, caliber... target shooting, duty carry, hunting, cc, etc.
I love my K9 with wood grips, but it is then as thick and heavy as a double stack polymer in a similar size... At least around the grips. If they came out with an aluminum frame double stack version of the K9 I would definitely be interested.
Smith and Wesson had some aluminum and/or steel frame SA/DA pistols I wouldn't mind having, but the only one I HAD to get was the 1006 (steel)... and later a 1911 clone in 10mm.
I really like my aluminum frame M9, but it is a big, fat, pistol for a 9mm. The slide safety can be thumbed off without changing your grip, unlike the old Springfield's (at least with semi- large hands). Plus, I think it is a joy to shoot.
I never really got into the Sig craze, but that doesn't mean I won't get one in the future. I hear a lot of pro- steel frame cc guys like the Bersa. I wouldn't mind picking up an aluminum frame 4" 1911 clone with a steel feeding ramp on the barrel like Springfield's. Even the Baby Eagles look interesting (slide is inside frame instead of over/outside).
Then there are always revolvers...
Although I rented many polymer pistols, my first polymer purchase was an HK USP45. After putting a few thousand rounds through that I had no ill will towards polymer pistols.