I used to site Fawlty Towers of one of my favourites but it's worn a bit thin now. Love all of the Blackadders but particularly the 17th c era one with Queeny and Nursey and Lord Melchitt, of the older classics I liked Butterflies, Dad's Army, It Ain't Half Hot Mum, Are You Being Served, The Liver Birds, Citizen Smith, The Good Life and particularly The Fall And Rise Of Reginald Perrin.
More recent ones I've liked (and frequently re-watch): Black Books, The IT Crowd, Big Bang Theory, The Detectorists, The Office, Extras, Outnumbered, The Day Today, Brasseye, I'm Alan Partridge.
As for fav characters from the above, phew, where to start...
Reggie Perrin, CJ, Richard 3rd (Peter Cook) Melchitt, The Spanish Infanta, The Witch Finder Pusuivant, The Baby Killing Bishop of Bath and Wells, Queeny (Blackadder) Moss, Roy, Denholm Reyholm (IT Crowd) Manny, Bernard, (Black Books) Ben (Outnumbered) Sgt Major "shuttup!" Rangi (IAHHM) Mrs Slocomb (AYBS)
Woolfy (Citizen Smith) Pike, Mainwaring, Frazer (Dad's Army) Margot and Jerry (The Good Life) Gareth Keenan (The Office) "Simon and Garfunkel" (The Detectorists) ALL of the characters in The Day Today and Brasseye ....and Sheldon (BBT)