Ronnie is the only Mitchell i've ever truly loved as a character. She really has turned into an Eastenders legend the last 10 years and there aren't that many modern day characters you can say that about. I'm gutted she's leaving, but at the same time i'd rather she went out while still remembered with fondness and respect rather than stick around for 10 more years to moan about the bins and who will pick the kids up from school. Samantha Womack and Ronnie have been an asset to the show, and while i'm not exactly riveted so far with the build up to her exit (although i've loved having Jack/Ronnie reunited) i still think i'll be sad to see her go and that they'll be a huge hole left when she's gone, i'm just hoping they'll pull it out of the bag for her actual exit episodes.
Louise is shaping up to be a decent character now they've toned down the bitchiness, she is only supposed to be 15 afterall. With some decent plots of her own she could have a very bright furture on the show.
I've always liked Grant (although his last stint was a bit pointless) and Phil, although it is time they rested Phil and let him grow old gracefully and not have him parading around 'owning' the entire square, some of us remember when he was the nicer, more sincere Mitchell brother.