The rackmount Digital Music Corp MX-8 (really old, used only) has lots of filtering options. This is what I use at home and I’m pretty happy with it - one thing I like about it is it requires no computer to edit - it’s pretty fast.
The Mutable Instruments MIDIpal does some filtering as well.
You can also use something like PD, ChucK, Reaktor, Max/MSP if you want to get fancy with the conversion or trigger macros, etc.