I have recently collated the data from the ten Saffron Walden, Colchester (and now Stirling!) singles tournaments since 2014.
Five most popular armies based on number of uses:
1 Chaos (16)
2 Orcs (13)
3 Dark Elves (10)
4= Dwarves & Tomb Kings (9)
And their performance based on average quartile position:
Dark Elves, 2.0
Chaos & Orcs, 2.7
Dwarves, 2.8
Tomb Kings, 3.0
For the other armies the limited number of uses skews the averages, but as the data grows they should become more usable.
Interesting factoid: the only WMR army not used in any of the ten tournaments = Vampire Counts.
Finally, I'm missing one set of results; the first Bunker Warmaster tournament in Colchester in January 2016. If anyone has a copy of them, please could you post them here or PM me. Thanks.