Still Tie Fighter (on Hard difficulty). I am currently on Battle 12 Mission 5, so pretty close to the end I think, something like 8 missions to go from the total 100 or how many there are.
At this point the missions are so damn exhausting that I usually have to take a long pause after a successful mission. There are a dozen things happening around you from the very beginning, you have to prioritize different tasks just right and be quick about it, if you want to be able to reach all primary and secondary objectives. I don't care anymore than much for the bonus objectives, nice if I am able to reach some of them accidentally, but that's all.
Battle 12 Mission 3 was a good example. From the very beginning (you have to be very quick especially about the first three):
1. change ship power settings to speed up, in order to get closer to the three enemy transports
2. request for backups ASAP (Shift-S + spacebar)
3. switch guns to dual heavy rockets, and hit each transport with one set of dual heavy rockets to get their shields low
4. concentrate on the third transport. When you get closer to it, try to disable it ASAP, hoping it doesn't kill you with its power laser.
5. Pray that your wingmen are able to disable the first two transports themselves, as you try to kill enemy X-Wings as fast as you can.
6. As soon as you see fit, go after the enemy shuttle in order to disable it. First use a single heavy rocket on it, and pray the shuttle doesn't get destroyed in the process. Then disable it. Try to do this as soon as you can, before the shuttle gets too far (and the friendly capture shuttle will have a longer trip to reach it). You can't usually do this before killing some enemy X-Wings first, as otherwise you may be having 4-8 of them on your tail shooting all the time while you try to disable the shuttle.
7. Try to keep the enemy A-Wings busy as they try to destroy the friendly shuttle that will try to capture the disabled shuttle. Too bad you have a slow gunboat which can't keep up with them that good.
It just seems you have to do all this in the exact order (which you learn by retrying many many times different approached, be very quick about it, and if there is even one small mistake (e.g. your heavy rockets get destroyed before they reach an enemy transport), it may be a better idea to restart the whole mission.