The Soldier is a relatively easy class to pick up and go. Automatic weapons are reliable and aren't worsened by lag as long as you're hitting your opponents. The Huggable is also a fun class not too difficult to use, but with low health you can die often, although I guess that's one of the challenges of using it.
I use the Soldier and Heavy. If you want to try the Heavy, it's good for competitive play if you know how to overcome its slow speed. Personally I'm not too fond of the Demolition or Chub Scout, so I could give you a bit of advice for the other classes if you want.