I'm more of a midsize fan honestly. Like adrift or complex. Ragnarok is a terrible map that only placates people obsessed with vehicles. As somebody who likes sneaking and mid range sniping I don't care for it. Haven on the other hand just feels annoying, not enough cover and extremely linear. All you really do there is play in a 2 story semi circle. --- "The only philosophy that is always right is that no philosophy is always right"
There's nothing wrong with the big maps, it's just that the gameplay doesn't mix well with them. With the addition of loadouts, if you want to stay competitive on a big map, you're pretty much edged in to using a DMR (or less so, Lightrifle). They kill the variety, in short.
Small maps allow more of a choice, because there's more chances for the close- and mid-range weapons to stand a chance. Using an AR or Carbine on Adrift would net you better results than using it on Ragnarok, for example. It promotes more weapon variety rather than DMR sniping and counter sniping.
In past halos, long range weapons were either map pick ups or starts, which is completely different from the loadout choice we have now. It makes the game play differently, in a way that doesn't mesh well with larger maps.