I am not in Barcelona and have no details about the impending strike, but last year I used the Aerobus from Placa Catalunya to get to the airport. It departs from the side of the plaza in front of El Corte Ingles and the stop is well marked, though you're likely to see a bus waiting there, anyway. You can Google for the schedule and fare (well under 10 euros last year). There may be separate buses going to Terminal 1 and Terminal 2, so check on your departure terminal before buying the bus ticket. There are vending machines right at the bus stop.
I am assumung "we" means just two people. If you are a group of 3 or more, a taxi might make sense. And of course if you're not staying in a part of the Eixample that's close to Placa Catalunya, you might want to opt for a taxi anyway.