I would change Nine things for BFG
The first would of course be balance. I loved the game to death but really it had all the balance of the tabletop game.
The second would be I would make the ships loreful. Which is to say somewhat in line with how they were in lore, power and otherwise. The Eldar moved quite differently than they did in TT, and they were also far weaker. The Void stalker was supposed to be one of the most powerful battleships in universe, but it was garbage. The tau, on the other hand, are supposed to have a garbage navy in universe but were OP pls nerf in game. This is especially relevant with the new factions coming in.
The third would be to truly make the races be different and have different mechanics. All of the races had lances that werent called lances and macrocannons that weren't called macrocannons. Besides the Eldar they had all the same movement, they had all the same ftl with different effects, and the same boarding. These should not be so similar. Making Eldar movement like TT would be a good start.
Fourth would be make maneuvering actually important. All games really just came down to flying in circles and shooting each other. Maybe make there maps with lots of obstacles to block maneuvering and places to hide. Reducing ability spam would help with this as all the AoE options helped get around people outmaneuvering you.
Fifth would be more types of ships, but they seem to already be doing that. To make this post constructive, I'll add I mean not just class variants, but also new classes, like dedicated carrier (not a cruiser which is also a carrier) and such. I believe I listed the majority of classes in my new ships thread, so those ones would be a nice start.
Sixth would be balance. Loreful balance at that. Instead of the Nerf bat the eldar received, they could have made them more fragile, but have dakka and speed to compensate. The Tau shouldn't have seemed like they came out of a fanfic, they should have instead have been allowed to bring more ships as the smallness of their empire lets them concentrate their navy more easily, which is why they can contest space from the vastly superior flee (see damocles). The Necron Fleet in the upcoming game should retain their insane 1v5 me and lose ships, but be very limited in their numbers (just like lore). Tyranids should have lots of ships and weird abilities, but the relative weakness at range and inability to target non "painted" ships from lore should concentrate. These kind of balance tweeks, not stat nerfing, are the way to go.
Seventh I would like to see ships alot more focused into their roles. In BFG1 they were basically, cruiser but smaller, cruiser but bigger, and really big cruiser. Instead of just being small and weak for example, escorts should be very maneuverable, which is their defense against big ships, and have ordnance they can actually use frequently (usually by the time the ability is recharged the escort is long dead. In exchange, give it limited shots. Carriers should have a lot more than one squadron, especially when it comes to fighters as their main role in battle is CAP. CAP for those who don't know, means counter air patrol, and involves intercepting other planes. The battle for midway for example split 624 planes across seven fleet carriers, which is about 90 planes per carrier. These carriers were tiny compared to the fleet carriers of 40k, like the Emperor class, so at the very least they should be able to match them when it comes to planes. Which brings me to my next point.
Eight. There should be more of everything. Guns, planes, torpedoes, ships, everything. Battles should be huge swirling messes, not slowly circling ships firing what looks like five or six shells once and a while. Warhammer ships are tough, capable of hours of unsheilded sustained bombardment in lore, they can take a bullet or two more than they currently do in game. Previously mentioned midaway, an averageish kinda small battle for the war, had 63 ships involved, 20 of which were capitol ships. I don't think its possible to get 20 capitol ships in game for a match. And that was a small real life battle. Big battles like Jutland (250 total ships and 50 battleships), the Battle of the Philipine sea (170 ships are 1.7k aircraft), or Leyte Gulf (304 ships not counting smaller craft like PT boats and subs and 1.8k+planes). These are the size of real battles. Hell, battles in warhammer are huge, with the Battle of Amarah, which consisted of all the ships a small sector could muster, containing on the imperial side 11 battleships, 60 cruisers, and "several hundred" escorts for a total of likely 371-500 ships (several means more than two but not much more) and on the necrons side 2 Cairn class battleships, 20 cruisers, ??? light cruisers and escorts (probably 52-78) for a total (stated less than a fourth, and far less in tonnage) probably about 74-100 ships. So that's a medium sized warhammer battle, and it contains 445-600 ships. I know the game can't render such battles, but it could at least have a couple more ships if it wants to really capture the true face of 40k space combat.
Ninth and finally, there should be more players and game modes. 2v2 only goes so far, especially with the tiny fleets allowed. Being able to matchmake against and find friends easier would be nice and make the above much more enjoyable.
Anyways, these are my thoughts. Hopefully this feedback helps Tindalos.