For non 8-bit leads that are more ‘newschool chip’, I prefer either zebra 2 or the native sampler of Renoise(3.0).
Zebra 2 has sample drawing and can morph between two waveforms.
If you own Reaktor Kontakt, or Battery…
I’m a very happy sidstation user, the thing is awesome I love programming the arplike stuff.
what about the odo synths??? click click
i got tired of using vstis that cant seem to get that authentic 8bit sound, so im going to buy a Shruthi-1 with the polivoks filter and just record and use it with renoise 
Famitracker is hands down my favorite way to make chiptune. It’s instrument editor is quick and easy and you can do tons of shit with it. I have plogue chipsounds and it’s just too cumbersome to me to design an instrument on it. The simplest little thing that takes 5 seconds in famitracker takes so much longer in chipsounds.
Deflemask is the next best thing. Not as good for NES chip, and doesn’t support expansion chips, but it does do a ton other chips besides including SID and whatever the genesis had. I wish deflemask had a dual SID mode like goattracker. If it had that, and supported midi controller input, it would be greatest thing ever.
Hand-drawn waveforms.