Preliminary results after 2 and a half weeks:
47 data points, most maps don't have a statistically significant (at least 3) number of games played. I'm assuming that there is a 3 minute turn around time between matches (game ends, results screen pops up, select new vehicle, join queue, get match, load match, finish countdown), and am adjusting the average times accordingly.
Of the maps that I can draw conclusions on so far, Leviathan has the best base credit multiplier per minute (CM/M) ratio of 1.55, and is tied with Cavalry for the best base XP multiplier per minute (XM/M) ratio at 0.33.
I'm not really in a position to play more matches at the moment, so I'll leave the current copy of the spreadsheet here for anyone who might be interested.