Reading. Keep them as far back as possible. Newcastle will finish first or second. Therefore we need to put as much distance between us and the pack. If we beat Reading/lose to Newcastle we'll be in the same position as we are now(in terms of the points gap) except we'll be two games closer to the end of the season. If we lose to Reading and beat Newcastle we'll potentially only be 2 points ahead of Reading and still a point behind Newcastle(same as we are now). I7ll take a safe second place over risking everything for first.
If we have to choose one then Reading.. the bigger the gap to teams below us the better..
Its as though you've both forgotten that Huddersfield (and Leeds, and Wednesday) exist.
If Reading were the ONLY chasing threat to the top two, then beating them, and extending that gap would 100% be the right answer to this question. But they're not. If we get cut adrift of Newcastle, and caught by Huddersfield and Leeds, then Reading being six / eight / a hundred points below us will be cack all consolation. We need to stay as high up the league as possible. Beat Newcastle, go top.