Hoo boy... There are
so many different factors that go into strings and a lot of hard science: the metals used for core and wrap wires; size of the core v size of the wire; shape of the wires; winding method; shape of the ball-end and how it is attached; treatments (platings, coatings, cryogenics, etc.); adhesives (used to stop wrap wire from slipping on round core strings); and even how excess adhesive is removed (solvents, acids and their environmental impact). If you're
really interested, read through Dean Farley's 22 part series of articles from Vintage Guitar magazine
here. Just bear in mind that Dean makes and sells a specific type of strings (pure nickel Snake Oil brand), so leans heavily towards them in his conclusions.
Every brand of strings (of which there are dozens) uses a different formula of all the above factors, and usually offer a few different sets. Also note I said "brand" - there are only about a half dozen different
manufacturers of strings in the world and these manufacturers make just about every set available. However, that doesn't make every set made in a factory the same - they are all made to the brand's order with very specific goals in mind
In short, there are too many factors to consider everything when choosing strings, making it far easier just to try a few different sets of commonly available strings and seeing what you like. The big two readily available in this country are Ernie Ball and D'Addario (Fender are barely a blip on the radar in comparison). Start with those.
