With all the available options on processors, your question is way too generic to support getting realistic answers. Do some more research before asking this question.
i bought one of these for on the fly tweaking, i got tired of going thru all of Alpines menus. think i paid around $50 on ebay. its a solid little unit
You forgot Audison. But again, without more detailed info on what the OP wants, something like a bit-one is simply me/us stating what WE like and feel WE need in a processor.