Some people on here just reccomend what they ride without even considering what the person wants. Ever thread you post says "Just get a 250f, it is better, because I have one..." :blah: Tougher than a 125 my ass.
Since you're an on-off rider, don't get a 4t, a 2t will be much easier to maintain. For the type of riding you do I'd reccomend a 250 TWO STROKE, but a 125 would be my second choice. For your intended riding, a 4t bike wouldn't be nearly as much fun to ride.