Line 1 was not crowded. I spent most of my subway time on Line 2 and Line 5, followed by Line 10 and Line 1 (and then the Airport Express, of course).
I started each day at 5 AM and rode on and off until most of the lines closed around 21:00.
I also rode the public bus system extensively. Some buses were full, many were empty.
Was it on the weekend or weekday? Just wondering because I take Line 1 every day and I feel like a cramped sardine. I wish I had your luck when taking the subway.