I'll use OEM parts if reasonably-priced, but not exclusively and probably not if they don't appear to be tangibly better.
For example, the Sienna has an Everstart Maxx and the Camry a Superstart Extreme. The Sienna needed a battery when at Walmart, conveniently, but I sought out an East Penn battery for the Camry based on research.
Wiper blades are probably some Rain-X or Michelins from Walmart or wherever. Brake pads I'm not fussy about - usually a mid-line store brand for these (BrakeBest Select Ceramics or something like that).
If I'm going to the trouble of ordering air filters online, I'll probably buy OEM. But if an OEM cabin filter is twice the price of a cheapo, I'll save the $10.
Spark plugs would be an OEM item, or at the very least, a well-proven substitute, given the difficulty of changing them. Ditto for other more critical parts.
A lot of the time, you wouldn't have too much choice (if your alternator dies along I-70, you'll probably get whatever the shop can get next day on the truck).
That's my thinking on this - just a case-by-case sort of thing for me.