First one I really owned was an Enya 15 C/L engine my dad gave me for Christmas in 1969, I was 9. It powered several nice C/L models over the next 25 years, a Jr Flite Streak being the best of the lot.

The first engine I ever flew with was prior to that, at age 6 I used to fly my dads Rudder Bug with a DeLong 30...even had photos posted in the old American Aircraft Modeler.

My first RC engine I bought with my own cash was a Veco 19 that powered a Kadet Jr back about 1979..."re-learned" how to fly RC with that one.
I currently fly a few Saito's, and have flown spark ignition SAM engines and several vintage diesels (loved that Amco 3.5) but still love the simplicity and power of a good 2 stroke.

It seems sometimes like 90% of modelers today either fly all electric or at least have a few in their fleet but I remain 100% addicted to nitro and don't see a cure in the near future.