best airport in Berlin
 

if we are staying in the city proper, which airport is best to fly into?

Whichever airport the airline takes you to that offers the best flight at the best fare at the most convenient time. Not much difference between SXF and TXL, international flights mostly still go to Tegel but will soon go to the new airport near SXF. "The city" is not easily defined due to the history of the four sectors - where exactly are you aiming for?

I agree with michel, above. I've never considered booking a flight based on flying into one airport or another in the same city. I go for the best fare. Why pay more money or be inconvenienced just to get to a particular airport.

A third vote for the best fare deal.

Both airports have fairly decent public transport connections; not exactly the same connections. Tegel would be considered "closer in" depending on where you might be staying/where your final destination is located.

Look, there are plenty of cities which have multiple airports in which the airport location DOES make a difference to some people so your question isn't exactly unusual. Depends on what you consider the "best" to actually be.

Whichever one is open.

Pa dum Pum (drum rim shot)

Thank you. I'm here all week. Try the bratwurst.