Ivarov hands down, he's a decent keeper by any standards and has always been the last one out for me. Harty was great in PES3, but isn't having quite the same effect this time around, don't know why. To me it seems harder to play with the default players in PES4 than it was in PES3, the defence just seems shot at times and it's impossible to stop the opponents attacks.
I miss Petipa, the growth player thingy was definately a great concept in PES3, kinda sad to have seen it go. Although I appreciate it that konami are trying to get as realistic with the game as possible, but I think that, besides the gameplay, it doesn't have to be spot on. I mean, when I want to manage a club accurately and realistically, I go for FM 2005. To me the managing part of PES should be more about fun than realism. (Not to an extent where it gets ridiculous or anything like that, but you probably get the drift...)