Hi, I'm a longtime fan, so I'm here to share my opinion. I am probably gonna be pretty negative in some aspects, but bear with me and feel free to disagree.
One of the main things that bothered me in AoW3 (which I liked), in contrast to AoW:SM (which I loved), was that although the battles were hugely improved, the strategic potential and creativity on the main map was pretty limited because:
1.conquest and map control became way too dependent on cities (you can't raze or occupy mines, there's really no reason for a garrison to leave the safety of the town. You can only expand by owning more cities), which ultimately lead to reduced amount of skirmishes and more doomstacking (your goal is always to take the enemy city - not his resources or mana relays) so your troops just need raw power on the battle map
2.I might be alone here, but the map scale was a bit weird for me. All your cities were at most 2 turns away from your next city, which kinda made units having high movement or forestry kinda redundant compared to AoW:SM, not to mention the vision range was pretty low for your units, which is, again, a consequence of there being relatively little point to skirmishing behind enemy lines;
3.terrain had relatively little importance - units could cross mountains without mountaineering and units just turn into boats on water (why freeze water for crossing when you can just wait an extra turn for free? Why have mountaineering when you don't really gain anything from it, or build forts on chokepoints?), which, though balanced, makes things quite boring;
4.above ground spells had relatively little impact on the game, ultimately feeling underwhelmed by the power of my all-powerful wizard. I wanted see more things like poison domain, summoning of evil woods and pestilence clouds, enchanting units with speed spells and all that jazz.
So what would I actually like to see in the new game? Well, related to my prior points:
1.you should be able either effectively disrupt your opponents economy with a small party of units, either by making resources be located farther from cities (so the garrison can't just pop outside the town for a turn without risk), or or there being other points on the map to capture for strategic benefit (dwellings were pretty cool, but ultimately pretty useless unless you invested heavily in them. Maybe they could provide special resources the devs mentioned on another thread?);
2.increase vision range to be almost on par with movement range in normal circumstances;
3.new planets I assume probably provide new hazards, so it would be cool seeing some terrain features that require a different approach (oh look, a super magnetic stone field, we can't have planes flying across this small patch of land, or some electric mist that ruins complex electric equipment, that just so happens to lead to the enemy resource site. Doesn't that require an interesting strategic approach? Just don't do what Civ:BE did and make it meaningless once you get some tech.)
4.I would love to see players able to change the land in some way. Maybe I could make a neuro-toxin generator? Some electro-static-shield thingy? Artillery emplacements to harass anyone approaching that ridge? Giving tanks special modules, allowing them to move much faster?
Anyway, just thought I'd share my thoughts for once. Love you guys, keep up the good work!