I'm playing in a high level core only game. Druid is better for many levels, but as I was coming in at level 17, I looked at druid first and found... wildshape sucks end-game. By that I mean, why wildshape when a transmuter wizard can spend 9 hours (18 if you have greater extend rod) shapechanged? It's just so stupidly ridiculously better, and (if using errata) no dealing with that bs "everything melds" crap, either.
Now...I know what you're going to say... "But, druids get shapechange, too!" Yes, they get a gimped version. Why? How do most DMs handle what creatures you "know" or "have seen" in a game you're just inserting your PC into now, without the year+ of in-game experiences at high level PC would typically have? That's right! Knowledge checks! Let's see, what knowledges for IDing monsters do druids get? Oh, that's right...Nature. In other words...almost all the crap you can wildshape into anyway and none of the FUN stuff (outsiders, undead/ethereal, constructs, etc...).
Oh, let's look at wizard. He gets all knowledges! And has every reason imaginable to have a sky-high int!
So...yeah. My rebuttal is that at higher levels in core only, shapechange makes wildshape practically irrelevant and druid becomes much weaker compared to wizard (or sorc, who benefits from having a high charisma for save DC-based Su stuff and has a better set of knowledge class skills than druid, too). Main advantage it retains is it can't be dispelled, that's about it.