Hi.
We use SS2 in our JV3. I think it's about the same as SS21, but correct me if I'm wrong.
It's stronger than the Eco Sols. If you have a fingerprint on the media, it will be enough for the SS2 ink not to "stick", but probably worse with eco. Aftermarket inks like Triangle, don't care about fingerprints and such, but are very high in solvents (and fumes).
Pretty much everything we print gets laminated, except banners and flag material, of course. If you do a lot of banners and stuff that's not going to be laminated, I would suggest solvent. With lamination, it should not matter much.
We are happy with SS2, but we vent the printer to the outside, and use a painters charcoal filter mask if we're in the room while printing. The fumes ARE harmful!
These are my opinions, that I have formed from firsthand knowledge with SS2, and research, mostly on this site. I have not tried aftermarket or Eco myself. I would think that the JV33 will be fine with SS21, as it comes with it from Mimaki. Do a search!
PS- are you sure you want 6-color? It's not really a fine art printer like a waterbased Epson, dual CMYK is a lot faster, and most people can't tell the difference, even with the prints next to each other... (At least on the JV3, but I guess I may be out on a limb here)