with the current built hull damage takes way to long to take out ships without special weapons, so you only care about boarding damage first and to a lesser degree about morale damage and weapon crit. chance second. if you are not a boarding monster faction, you try to take out the flagships deck against factions with morale and if you succeed, you sent it routing with repeated rams and other sources of fast morale damage. if the flagship is routed, you do the same for the remaining line ships. against factions with morale immunity, it is a race about who hulks whom quickest.
nids are the undisputed top of the food chain. you don't want hiveships, you want infestation devourers. a list of them has more boarding attack per charge, more troops, more shields, more hangars and more crit-slots per fleet plus access to tentacles, more escorts and only slightly less hull per fleet. you have to spend one upgrade for the synapse upgrade, so you cannot have 10sec temp crit repair and the faster shield regeneration as the only real drawback. the tentacles are key to increase your effective range. their pull has roughly 7.500 range and can be chained to pull stuff into your boarding range. together with the movement burst you have an effective killzone of roughly 9.500k against eldar and 10.500-11.500k against all other fleets (you move your base speed plus 4000 distance in two seconds, eldar can burst for their base speed plus 2000 distance in the same time). the void lurker skill gives your flagship additional 9000 move burst in 2,5 seconds. on top of that, they have the psychic scream, which is extremely good to break morale.
there is no way kin-crewed DA BB can do anything against that. their attack range is in the nid killzone. the only way to beat that list is to be lucky in out-capping them with silent running eldar (lucky in not running into any hidden ships and you need a map without three clustered VP). anything silent running without the eldar burst and instant-turn is probably too easy to catch.
I will maybe write some stuff about other fleets, for example I think there is no place for lances atm and I think you undersell SM.
edit: corrected the tentacle range. somebody should test, if you can reliably burst away from it as eldar before the tentacle can connect.
the nid assault boats charge is used up, if they reach an enemy ship. I think the problem is that turrets takes longer to clear the nid fighters than it takes to launch the next wave.
if you go all in on hangars with the other fleets, you have a low ship count / weapon damage fleet with at best 96 fighters and around 60 turrets vs 160 harpies per charge (with both having the same stats except speed). fighter dogfights are pretty quickly resolved, so I doubt any turret support will save your fighter charges (would need some playtesting to confirm). but even if that would work to neutralise offensive nid ordnance use, you have nothing to take them down in a reasonable time frame. you can't use your numerical weaker ordnance in an offensive manner, you don't have the dps to get through their shielding and hull and you can't board them. the nids contrary to that, have several tools to get into boarding distance or they could just take and hold three VPs and do some shield cycling.
I think necrons have an increased damage reduction now and the engine seems to be extra protected against crit. damage. this does not help them at all, because one of their main problems is their slow map speed. nearly all fleets can kite them easily with their engines intact. their extra survivability only means, that they lose most of their subsystems before getting destroyed. another problem is that they can be boarded pretty hard, because their troop/point cost is really bad.
personally I want to avoid using animation loop exploits. imo it is okay to boost away from incoming ordnance, but I think it is not okay to keep them in a repeating animation loop.
the BCs are not fragile at all, it takes minutes of focus fire to kill one devourer. maybe I have to ditch macros and go lance-boating again, if the new armor system nerfed macros. I would not be surprised if nids have as a hidden perk less crits overall, because they have less targetable subsystems. in the time I would cripple two to three other ships, I barely have any fire effects on nids for example (their brains tend to blow up pretty fast though). the whole crit-system is pretty obscure atm. necrons seem to lose half of their subsystems before their engine blows, roks don't even catch fire, if you don't board them and SM seem to suffer crits as fast as before.
I know, it is technicially not 1.200 points, but people can still use old over-budget lists and it would work nearly the same with 5 devourers and for example 3 strangler escorts. the tentacles keep you in boarding range and engine crits prepare the assault boat coup de grace. the hangars keep you busy, while you try to keep the gribbles at +12.000 range. I don't think you can outrun it with 200 move speed for long, especially with all the hangars you have to deal with. you can't do much with crits against nids (at least with macros, don't know if there is a hidden lance buff) and other fleets cannot stack enough hangars reasonably to counter it. atm it feels a bit like trying to tackle slaneesh chaos with eldar in the first game. so I am open for some suggestions.
if you want to keep it general, I think you can say that carriers are overpriced and torpedo boats to a lesser degree too, mostly because anti-ordnance turret plays are very strong. the tau gimmick with escorts hooks is bugged atm, but I don't know if it is cost-viable to take a ship with hooks instead of paying for a hookless ship from the same weight class + an escort individually. I would say that high armor is overpriced too, because it has no protection against crits. you can see how these three factors combine to make the SM fleet pretty miserable to play.
I think you underestimate speed and silent running. the first game was dominated by speed and detection. I think the cap-point system makes it even more valuable to be fast and stealthy.
other stuff like CR, BCR vs GC and BB need to be looked at more specificially for each faction individually. that said, the GCs always had a trade-off for their health/firepower per point cost, BBs often worked best as a MWJ flagship and the cruiser lines for navy and chaos have both very good ships compared to their BC choices.