Coleman- Rarely knows his best squad, likes younger players doesn't stick to a certain style of play, his teams don't look very motivated tactically better than dowie.
Dowie- Signs the old guard, likes big wingers decent attacking style of football often leading to you receiving a hiding, tactically shocking but good motivaton.
Coleman has a good eye for talent spotting, can get you good young players for cheap who then become some of the better players in the league (Westwood and Gunnarsson prime examples). However he will not motivate your team as he believes in players who should already have enough about them to motivate themselves. Tactically I think he does prefer to play the passing game but in the end it was mostly longball to get us out of ruts which was ineffective once our target man had left last season (Best). I like Coleman but I'm not sure he is the right man for Preston, I think you need someone who will be tough on the players and take no shit (Jim Gannon? Not sure what he's doing now... seems to do well with relegation fodder, no offence)
Can't remember too much about Dowie but I was disappointed when he got the sack. He's very scientific in his approach, again I'm not sure if he is the right man for Preston although having said that he turned Palace from relegation fodder into a team who got promoted in a very short space of time but looking at his overall record it may have just been a one off or beginners luck.