bitflipper
"Great bitcrusher" is an oxymoron in my world 
 
A bitcrusher works by truncating data to some user-specified word length. That's it. There aren't a lot of possibilities for adding flavor and features to such a simple process beyond letting you specify the word length and applying before/and-or/after filters.
 

This ^.
 

As mentioned above, D16's Decimort has about every knob and button you can imagine tacking on to a bitcrusher.

Most of which are apparently for the type of filter you mentioned plus downsampling rather than the actual bit reduction part.

Hi bitcrush....... ehhhhh bitflipper,
you reveald yourself .Now everybody knows that you are a bitcrusher,
not a bitflipper.
But you are happy why everybody here knows  you by this name.
I ´m thinking about an initiative on this forum abouit bitflippers using wrong names,
perhaps a thread like 
bitflipper is cheating us all because he is a bitcrusher , 
no $$$ for Cake and off to another sequencer!
 
 
 
 
 

I'll admit to having crushed a few bits when I was young and foolish. But I quickly realized the error of my ways and adopted this guiding principle: 16 bits or more in all things.
 
I just happen to have Decimort here (got it in a group buy a couple years ago that included all their effects) but I hadn't ever used it so I just now loaded it up to have a look.
 
For all the knobs on it, the functionality is simple. It lets you select both word length (down to 1 bit!) and sample rate (down to 44Hz, with optional anti-aliasing filter), and it has a single filter (of selectable type) that can be placed before or after the decimator. There's a wet/dry mix control plus input and output level controls.
 
So I couldn't resist trying the buggar out for grins. When used in moderation, it gives an effect reminiscent of singing through Atlas horns at the racetrack (we've all done that, right?). Not entirely unpleasant.
 

I am a  fan of d16 stuff, so will say their plugin.. (buy the bundles.. sale is currently on)
 
 
but if you are on a budget (free)
http://www.kunz.corrupt.ch/?Products:VST_TAL-Bitcrusher
 
I'm also a fan of TAL as well.. which is an issue as TAL put out their sh-101 emulation recently which is good, but I already have D16's Lush (roland missed that boat :/ )