If I tried to go for a complete collection of individual developer/publisher Renovation would be at the top of my list. I don't think I ever will though, and I'm fairly content content with having El Viento, Earnest Evans, Gaiares, Valis III and Whip Rush either boxed or complete for the Genesis. If I tripped over Elemental Master, Valis or Granada boxed in the wild I'd surely pick them up.
I've got Road Avenger and Time Gal on saved searches on ebay but I'm not paying the prices I've seen all year for them. I accidentally passed on Revenge of the Ninja earlier this year, a collector here in town asked me if I wanted it and I forgot to pick it up.