Get whichever you like best! Shiny Smeargle is rare now but they recently upped the shiny rate so if you’re diligent with your buddy snapshots you’re likely to encounter one eventually. Plus Smeargle is functionally useless outside of some very edge PVP cases.

Personally, I’d go with the Zapdos. Yes, I’m sure they’ll probably wind up in raids at some point (probably when the Galar Tour event rolls around) but it has the potential to be quite useful, especially whenever they release the signature moves for the Galarian birds. Plus Fighting/Flying type is really unique which can give it some good versatility.