I can provide some insight on civilization performance from the current patch which hopefully can give some food for constructive discussions/civ talk. 
RM - All Maps - All Teamsizes - All Ratings
Top 5 civs in descending order (all within 0.5% of 52% winrate):
- Franks
- Indians
- Berbers
- Huns
- Goths
Bottom 5 civs in ascending order (all within 0.6% of 47% winrate):
- Chinese
- Byzantines
- Vietnamese
- Burmese
- Saracens
New civilizations from the Dawn of the Dukes expansion:
- Bohemians - 48.53% (additional info: top 5 civ in Arena 1v1 specifically, lower than average winrate on Arabia)
- Poles - 50.47% (Poles also perform very well on Arena with an average performance on Arabia)
Of course it can also be important to know filtered information related to specific maps/ratings/teamsizes/… but to give a small insight until the community stats website(s) update to the current patch.