Your friend doesn't know what he's talking about.. There's no such thing as the "best" set of strings... there's a vast variety of different types of string, which are selected for reasons of personal preference or application... The best set of strings are the ones that feel and sound the best to YOU... You'll just have to go out and experiment with various brands, gauges and materials before you can determine what the best set of strings are...
Personally, I like Ernie Ball Regular Slinkys... Some people hate 'em, some people love 'em... It's up to you.. I also use D'Addario XLs on certain guitars because they sound better on certain guitars... D'Addarios are very popular, but that doesn't make them "the best".
Older guitars are not inherently better than newer guitars... I don't know what your friend is talking about if he's referring to a guitar made in 1999 as opposed to a guitar made this year... And if he's talking about vintage guitars, that's a bunch of nonsense... People perceive value in vintage guitars because they are old and there aren't many of them around... Much like comic books from the 50's or 60's... Somewhere along the line, someone drank the Kool Ade and convinced enough people that a 1957 Les Paul has some magical tone to it, that can't be replicated today, because it's old... the fact of the matter is; there were far more variables in guitar construction and electronics than there are today... The product is more consistent and the methods of manufacture are better than they were "back in the day"
there is the case of a particular model that has undergone subtle changes in manufacturing over the course of a few years, but that depends on the guitar, the model, the manufacturer, whatever... You can't make a blanket judgement and say that all guitars were better 10 years ago... That's too simple to be true..
The sound of a guitar comes from the wood it's made of, and the pickups that are in it... The pickups are really the biggest factor that affects tone.. Epiphones are cheaper because they are made in China (used to be Korea) and they cut corners on materials, construction and labor... Gibsons are so expensive because they are made in the US by union employees and they think the name on the headstock is worth another $1,500 - $2,000.
Oh, and they're finished in Nitro Cellulose... Yippee!