The Picasso-IV is simply the best Zorro based amiga graphics card bar none. It has it's own mini PCI bus (or something very similar) that allows all kinds of add ons, including a TV module, soundcard etc.
It does lack any form of 3D acceleration however (less of a problem unless you want to play 3D games that support OpenGL etc).
Of the remaining amiga specific cards, the CVisionPPC is more powerful (based on a more modern GPU and has more memory) but it's no use without a cyberstorm mk3 / cyberstorm ppc accelerator card. It also lacks the SD/FF hardware and has no further expandibility.
After that, it's a PCI bus board if you want to use various off the shelf PCI graphics cards (as well as sound cards, NICs etc). The Voodoo3000 is particularly well supported. However, the display quality of the Voodoo is simply awful IMHO ;-)
