From airport WAW to downtown

I’ve always taken a taxi. They are very cheap in Warsaw. Just be sure to go to the official taxi line/stand. Ignore anyone who approaches you elsewhere. I’ve heard the bus is easy - it really depends on where in Warsaw you are going. It’s a huge city with lots of sprawl.

I had a trip planned to Poland, arriving in Warsaw, for this month. If I were arriving at night (I'm a solo traveler) I would have taken a taxi. Since I was arriving in the daylight hours, I had planned to take the bus or urban S2 train line:

S2 train line from Warsaw Chopin airport:
https://www.wtp.waw.pl/en/timetables/?wtp_dt=2020-01-12&wtp_md=3&wtp_ln=S2
Price: approx 4.4 zloty (approx $1.17) for a 75 minute ticket
Journey time to my hotel would have been 41 minutes, including a 10 minute walk.

Bus 175 from Warsaw Chopin airport:
https://jakdojade.pl/warszawa/rozklad-jazdy/linia/ZTM_WARSZAWA-175/kierunek/0?d=now
Price: approx $1.15
Journey time to my hotel would have been 34 minutes, including a 3 minute walk.

These journey times and prices are based on my hotel location, roughly near Nowy Świat-Uniwersytet station and would vary depending on your exact destination.

Everything is safe - bus, train, or cab

It’s been ten years since I was last in Warsaw, so confirm beforehand - but I always just took a taxi. Just be sure, as others said, that it’s an official taxi. My first visit, I was alone, jet lagged and overwhelmed, and a nice man who spoke English said he’d give me a ride. I followed him to his car and it was only as he opened the trunk that I remembered what I’d read in my RS guide - unofficial drivers will try to pick you up, only take a real cab. To be clear, I never thought I was in any danger. Still, I apologized, grabbed my bag, and high-tailed it back to the terminal. My memory is that the cost was at or less than 50PLN, including tip, from the airport to the central train station, or to Hotel Mazowiecki, where I always stayed. I always felt safe, but, as a single female, always stayed alert - as I do everywhere, not just in Warsaw.

I took Bus 175 from the central station to the airport once. It was very easy. Not sure if this is true or still the case, but I had heard that you had to buy an extra ticket if you had a large (non-carry-on) suitcase. So I did. Of course, the bus didn’t get spot-checked, and I keep the extra ticket in my wallet as a reminder of my time in Poland.

We took the train both ways. It’s been a few years so I don’t remember the details.

I took the bus in 2018, and it was fine. There was a stop relatively near my hotel. For other locations, a different option might have been better.

There was a ticket check on my bus, and at least one passenger was fined for riding without a ticket.