Need to replace a 12' wide double sliding glass door that goes from my living room to my back yard. (2 stationary side panels / 2 sliding panels - each 3' wide).

I don't know anything about best materials (in PA, so winters get cold), brands, pricing. . .

Current door leaks air like crazy, frame is coming loose from the glass on one of the stationary panels, one side is really tough to open/close. Had the guy that made my mirrors and replaced the glass in one of my widows take a look - he said he thinks it is original to the house, so probably over 50 years old. Said it was time to replace, but his company doesn't install sliding glass doors, so he couldn't offer any advice or pricing.

Any guidance/advice is welcome.