Here are the results of the survey! I haven't done any analysis of the results other than what Google generates automatically, but for anyone who is interested, here (warning: predictions may contain spoilers) is the raw data of the 5,670 responses. Every question was optional, so each question was answered a different number of times. Thank you to everyone who participated!

How would you rate Season 6? (5,104 responses)

The mode was a 1/10 (26.7%). The second most popular option was a 3/10 16.7%).

Compare each season

By far, most people found Season 1 the best and the most popular opinion on the worst season was Season 6. Seasons 1 and 2 seem to be the most popular, and Season 5 was the second least popular.

Which actor had the best performance? (4,873 responses)

Michael Kelly (Doug Stamper) was the most popular response (34.0%). Robin Wright (Claire Underwood) came in second with 22.5% and Boris McGiver (Tom Hammerschmidt) in third with 12.3%. The options were randomized for each survey to ensure people weren't biased by the order. Here are the top 10:

Note that "Kevin Spacey" were all write-in responses.

Which chapter was your favorite? (4,035 responses)

The most popular episode was the season opener (Chapter 66) at 26.2%. The second most popular was Chapter 69 at 15.3%. The finale (Chapter 73) was the third most popular at 14.1%.

Should there be a season 7? (5,007 responses)

67.2% don't believe there should be a season 7, while 18.9% believe there should be, and 11.2% responded "Maybe". The other responses were filled in by the users as write-in responses.

Was this season better or worse without Frank Underwood being in it? (5,033 responses)

80.1% believe the season was worse with Frank Underwood not appearing in it, while 5.7% believe believe it was better. 13.2% are indifferent. The other responses were filled in by the users as write-in responses.

Should Kevin Spacey have been in this season (5,050 responses)

58.5% believe Kevin Spacey should have been in the season, while 27.7% believe he should not have been in the season. 12.0% responded "Maybe". The other responses were filled in by the users as write-in responses.

Anything else? Future season predictions?

This was up to users to fill in. You can see the responses in the responses link above.

Here are the results to season 5's post-season survey if you would like to see those.

Thank you for participating in the survey and in this subreddit! I hope you found this survey interesting. See you next season (if there is one), and feel free to stick around for off-season discussion!