windows messenger is easily the best. it's not bloated like msn, it has the best gui, it doesn't have the horribly sounds aim does, it's the closest to aim, but has a better look so it winds by the 1 point.
i'd use aim, but all the people i deal with in real life are computer users, but outside desktop publishing - by which i mean typing homework in ms word - are computer illiterate so the flashy 5 year old features used in msn appeal to them, and i'm forec between using msn and talking to people or aim and talking with 3 people.
oh the burden of choice.
msn 3 was the been knees. windows messenger is as close as i'll ever get to msn3 again.