Get the Meditator.
I got a 4000D Meditator plus Voodoo 5500, plus a few other cards on ePay for about the same price as a Picasso IV.
You probably won't get such a good deal, but a Voodoo in a Meditator will run circles around any other RTG video solution available for the Amiga. Plus, you have the side benefit of using other PCI cards, notably 100-Base-T ethernet assuming you're not using OS4.
Also, hopefully someday (soon!) someone starts selling OS4 compatible PPC cards for the Meditator.