Ghost suggestions: Change cost to 100/200 or 100/150 from 200/100, increase cast range of nuke and revert snipe back to the old version.
Reason: since the ghost should compliment bio and bio needs minerals and not gas, this will make ghosts more accessible for bio, but in turn make them worse against protoss. Mech should have other answers to protoss that aren't the ghost, such as different tanks. The increase of the nuke cast-range is to break turtle scenarios in just about every matchup. This gives terran the ability to break heavily defended locations since the siege tank was nerfed in its ability to siege thanks to other units such as the tempest and viper. The cloak and small size of the ghost makes it hard to detect, and with a longer range, can be used to break locations more reliably. Better nukes would help unstale games in the lategame, and fits well with more positionally based games. The new snipe was an attempt to make ghosts relevant vs zerg (and as an answer to ultralisks and broodlords), but in doing so, they lost a lot of their power against protoss. The snipe-emp-storm-feedback battle vs protoss is very intense and a bit underexplored, and by changing snipe (which is a nerf in these scenarios), these microbattles might become less and less frequent. I think the old snipe was perfectly fine and should be brought back. But then how does bio deal with ultralisks and broodlords? The raven should be the unit to help to that, not the ghost.
Raven suggestions: change HSM cost to 100 or 75, change auto-turret energy cost to 25 and increase size by a bit (keep building size as 2 of course), and maybe nerf its duration to a few seconds.
Reason: ZvT bio is a battle of micromanagement and very fun to watch and play. I argue that terran has an advantage in the early-mid game, and zerg has an advantage in the lategame. Because of it, it should make sense that ultras are so strong. As such, I don't think ultras should have an easy counter: instead, they should be hard to counter, and dealing with them takes skill. The raven can be the new science vessel vs zerg, providing powerful utility spells and needed detection. The new auto-turret should be a very potent spell that is difficult to use. It can be used to block pathing of the enemy zerg army, making it harder for ultras to engage into bio. This isn't a point-and-click solution to ultras and it doesn't make them completely irrelevant: the turrets can still be destroyed and played around. But I believe that successful use of the turrets will help, but only if used correctly. Also, the turrets do 16 damage per shot, doing decent damage vs the ultra's heavy armour. The larger size is to emphasize this role, and the much lower duration was to ensure massing ravens wouldn't be viable. As for seeker missile, it can also be used as an anti-ultralisk spell and terran's answer against lurkers since tanks aren't very strong against ling/bane comps. Plus, terran constantly needs detection for creepspread, possible baneling mines and lurkers, so the raven should be that constant detection. With all this said, it will be important for the terran to decide whether to use turrets or seeker missiles against the enemy army, and they must be protected or else they would get sniped by mutalisks.
Both spellcasters also serve a niche role vs terran: the HSM and turrets are used to break siege lines, and the nuke is an extreme siege-line breaker. Ravens might even see use vs protoss, but I think banshees and liberators would be better. Nukes would be useful if the terran creates an unbreakable siege line.
Small suggestions. I might be a lunatic and be completely wrong, but who knows.