The Viggen is what made this game click for me. It is forgiving with speed, had some give with AoA but makes it clear when the pilot pushes that too far. The tutorials are very good for someone with minimal flight sim knowledge, and flying low made it much easier to acquire targets when I was learning, although I think target spotting should be better now with everything.
I do think JohnathanWinters has a point too with the Mirage, I was about ready to quit DCS because the Su-25T was so tough to fly. The Mirage gave me hope because the act of flight itself was so easy. Ultimately I moved on to the Viggen because I struggled learning the cockpit due to it being in French, and the manual at the time wasn't as informative as I needed, but the manual has been updated since so that might be different now, and maybe OP's friend's memory is better than mine.