My favorite 4v4 TMM maps:
Mangrove Delta
Forgotten Archipelago
Maridia
Metir
Basically, I love navy maps with an emphasis on frigate raids, t2 navy, and torps. These maps in particular are very much the sweet spot for me in terms of aggressiveness. Other navy maps like Headland, Lena River, Lost Archipelago or Saskiya are a bit too large/turtely for me. Still ok maps, but not great.
Good 4v4 land maps:
Monument Valley
Plateau of arracis (haven't played it much, but I enjoyed the 4v4 on it so far)
Here I like asymmetry, larger than 10x10 so TML and firebases arent too dominant, not some kind of winner-takes-it-all mex or reclaim distribution.
My least favorite 4v4 TMM maps:
Seraphim Glaziers (usually decided after 2 minutes by bomber vs transport)
Winding river (so much wrong here. River too long and narrow. Corners 100% contestable winner-takes-it-all. After winning mapcontrol and having 3x the eco the game drags out for another 30 minutes because you cant actually attack bases with land/navy)
Adaptive Kusoge (bottom 2 slots too open. 20x20 diagonal is just too big for a pure land map)
Sands of Ablicka (<2km rush distance on top lane and very contestable reclaim)
Syrtis Major (just awkward middle relcaim and lots of chockes)
Sirgis (too spread out, fucked side slots)
any very linear/lane-oriented and symmetric 10x10 land map
Seraphim outpost (basically 4 1v1s next to each other, with whoever wins his lane first then just dominating all other slots with air)
Delta river (too turtely)
Strife of Titan (you spwan like 1km away from an enemy in 4v4)
While compiling this list I came across a couple maps that should be considered for 4v4 tmm:
Turtle Beach
Adaptive Ocean Crater
Skadi
Krakens Nest
Madness -8-