I don't remember when exactly I became a fan of M*A*S*H but I do know that I was well before the series finished in 1983.
As the reruns kept going through syndication, even to this day, I grew more and more familiar with the series. I love the comedy and I also enjoy the topical aspects of the drama. My favourite piece in this regard comes from Hawkeye's experience being blind in Out of Mind, Out of Sight in season five. But there are many others.
However there are episodes that for various reasons I just can not watch. For example, acute embarrassment has it's limits and that line is crossed in Edwina (season 1), Love Story (season 1), Tuttle (season 1) and Henry in Love (season 2). I also can't watch Hawkeye (season 4) despite it making perfect medical sense. And there are others.
I don't really have a favourite character. Everyone is wonderful in their own way. I also don't have a favourite episode as there are too many.