I tend to play Soldier, Medic, or Sniper these days, and occasionally Demo. I can still rock as a good combat Engie, though.
For new players, I'd recommend Soldier or Heavy. They're basic classes, and generally people won't yell at you for making a mistake with them. Heavy is one of the most skill-oriented classes (as opposed to strategy-oriented, like a Spy), so it doesn't have many tricks to master, making it a good choice for a beginner.
Above all, though, I'd advise you to try out every class for a few rounds before discarding them. They're each suited to a very different style of play, so it's likely you'll find one that suits you before long.
