Why didn't Michael Okuda say "Buy TNG Blu-ray sets to get DS9 AND VOY on Blu-ray!"?
Obviously, so he can say "Buy DS9 Blu-ray to get VGR on Blu-ray." soon.
I think Emissary, The Visitor & Trials & Tribble-ations would be my choices for a sampler if they went that way. They can include the updated TOS blu ray footage in Trials too as an added bonus.
Is there actually any original TOS effect in there? IIrc, all effect scenes are newly done for that episode anyway. If not, it hast to be mastered in multi-angle, of course, so you can choose original or updated TOS effects, just like you can on the TOS Blu-rays.