I like the concept of turning into other creatures on my own volition. There's a prestige class in third edition called the Shifter which allows for changing into various forms far more than a regular wild shape would allow, such as humanoids, oozes, plants, constructs, dragons, and outsiders (I could turn into an Achaierai if I wanted to). It also comes with full talking capabilities in any form provided by wild shape so I can be a talking animal temporarily. Version 3.5 has a nerfed version of it called the "Master of Many Forms" which has less available form groups to turn into (no outsiders means no turning into an Achaierai) and no unlimited form shifting at max level.

The closest official option in fifth edition is the Druid's Circle of the Moon which provides slightly more powerful forms to choose form, but doesn't allow for anything other than slight humanoid changes, elemental forms, and stronger beast forms, and doesn't provide the ability to speak in wild shape. Unofficial classes such as EN World's Morph class try to replicate that Master of Many Forms experience.

What's your favorite prestige class?