Magazines and shops mostly. My father gave me a huge XT PC and I used to play it all kind of crap looking adventurish games all the time. PC gaming was still in it's very infancy and the amiga was growing strong with the A500. My friends where still playing with their C64's and these dull 8-bit consoles.
As my parents wheren't really rich those days I had to convince them to exchange the giant pc for an amiga. My father and an uncle, kept on telling me "but but but these pc's are the future, you will be very sorry in a couple of years time". I didn't care and I didn't really believed in it neither because eh just look at that thing. Besides that, I wanted that F-18 Hornet flying around in MY bedroom instead of behind the shopwindow from the shop I camped far too often. After showing my dad Amiga screenshots from several magazines and a lot of aditional whining he decided to exchange the pc for an amiga 500
Very later on, around the DOOM days however, I did sell my A1200 to get me a 486 pc but that's lot's of years later.
Now I have both amongst other videogame relics