Interesting, the data looks like almost every rank prefers 10km the most; yet the map pool for lower ranked players is overwhelmingly 5km.
While I understand to some extent the logic (in that playing on 5km lets you get good at basics of t1 tank spam and there is probably less to manage than on a 10km), the problem is that it leads to very repetitive gameplay that can quickly get tiring.
While I'm aware that personal preferences will vary (so there's very limited use in my own experiences), for what it's worth when I started with ladder I quickly got tired and switched to astro crater because of the lack of variety in a 5km tank spam game (yes, astro crater was much more varied and interesting to me! This is the low mex version that used to be played though). It felt like there was little room for alternative tactics and most games played out the same (further compounded by T1 being the stage with the least variety of unit types and other than Aeon, minimal factional differences).
Looking at the map pool, despite 10km being a preference for all ratings except 300-500 (for which it was still 2nd favourite) based on FtX's old survey, we have 100% 5km for <200 and 75% 5km for 200-700. Now I suppose you could argue that if you get good at managing your eco in a 5km and good at building the maximum number of tanks, coupled with a good build order and sensible use of your ACU in combat you should be able to get past 700 rating relatively easy. However, I suspect I won't be the only one who was turned off by what felt like a grind of optimising a single approach (spam t1 tanks).
Has anything been done more recent to see if lower rated players really do prefer 100%/75% 5km maps?