iPhone 4 imo. If not iPhone, then an Android phone without doubt is the best alternative (it is probably better than iPhone). The most powerful Android phone yet is HTC Desire and it has been rated 5/5 by sites like Techradar (the iPhone 4 managed a 4.5/5).

So go for iPhone 4 or HTC Desire (or HTC Desire HD if you want a better camera).

Oh and on a side note, Motorola Droid is already too old.