What airport near San Francisco (say, max 50 miles) is easy for
national air journeys, meaning not many queues etc. Maybe Oakland?
Anything else? Thanks

Conditions at all three airports are very variable. Oakland is in
general less busy than SFO, but I've waited in unbelievable lines for
the xray at OAK in the morning. SJC is perpetually under for
construction and one of the two runways is closed now while they make
it longer.

As others have said, it probably makes more sense to use the airport
that's easiest to get to from where you are. If you're not driving,
BART goes directly to SFO. BART stops at the stadium near OAK and
there's a shuttle bus. SJC is between the Caltrain line and the San
Jose trolley, and there's a shuttle bus connecting all three.