GNW Tenten is pretty hot with several new builds atm. If you plan on running one of those she's pretty important, although on her own she won't do too much. Even if you don't run her for your main team she can be a top damage dealer in ranked on her own.

Refines are super important though, one of a handful of sources for initiative which is vital.

Do you have mei or darui? Grab tenten. If not (or you have no desire to use either of those or aren't a fan of chasing the meta) then the refines are a safe bet.