Whether or not to kill the bombers over the fighters first is decided by several factors. A big one is what your basic goal is at the moment. While bombers are not an immediate "personal" threat, it can be very important to kill them, and to do it quickly.
If you are actively engaged in defending a base killing bombers is a large priority. To not kill them could mean losing your hangers and eventually a base. Bombers are also a priority if you are defending your HQ. Defending a CV is another example where killing bombers would take priority over killing fighters.
Sometimes even if all you're doing is furballing bombers can be a big priority. You don't want them leveling the FH's and killing the fight. So you need to protect both sets of hangers in that instance. Yours AS WELL AS the enemies. Yours are easy enough, just kill the enemy bombers. Defending the other teams is more difficult since you can't kill your own teammates. I usually just won't defend them if they're intent on killing the furball.
Other times, killing the fighters is a bigger priority. Capping a base is an easy example, as well as participating in a mission and defending your teammates.
If you are just out trying to score some kills and stay alive, you need to neutralize the biggest threat first. Maybe that means killing it (the threat), maybe that means just forcing the bogie into a weaker position. I prioritize threat based on height, speed and turning ability. Killing planes equal or higher than you is the first key. I also put huge importance on killing fast planes if I'm high, and good-turning planes if I'm low. Up high a 109, P51, 190, etc is more dangerous than the N1K, A6M or Spit who can't catch you. If I'm on the deck I put more priority on killing the better turn planes such as the N1K, A6M, and the Spits. 109's, P51's, 190's, etc are not as dangerous (unless they are above you, or have that potential due to their speed).
I don't worry about LA's unless they have some buddies. I worry about all F4U's unless they are way under me.
Sometimes to kill the biggest threat may mean killing bombers, but if they have an escort you'll need to deal with them first.
To "deal" with the escort in order to kill the bombers often times does not mean killing the fighters, but rather fooling them into a lower position where they can't defend anymore. If you turn once or twice to deal with the fighters you will be out of position to kill the bombers. If the escort turns with you they will be out of position to defend. If you have help things go much better because a few of you can concentrate on the fighters while the rest kill the bombers.
If you can seperate the bombers from the escorts, or at least convince the fighters to get too low you can kill the bombers fairly easily. The best defence bombers have is the escort. Remove that and the bombers are pretty helpless unless they are high.
Bombers below 16K are easy kills unless you attack from the back. Those that are higher are a lot more difficult. Faster bombers are also harder to kill than slower bombers. All bombers are fairly easy to kill with the correct tactics, but it pays to look closer at their strengths and weaknesses.
I would say I rank bombers by ease of kill to be- Lancs are easiest, followed in order by B24's, B17's, and B26's. I don't include Mossies, 110's, B5N's, etc. (Some may include P38's too, hehe). The KI-67's I seldom see off the deck, and are easy to kill as well. If they get up they would be tougher I'm sure. Lancs are just plain helpless. B24's, 17's and 26's have much better guns, and are faster. B24's catch fire with just a few hits from the .50's, but B17's are tougher. B26's are fast and have good guns. You need to appraise bombers for their strengths and weakness too, just like a fighter if you want to win.
The more dangerous bombers are best attacked low (15K and under). As the more dangerous bombers get higher, they are much more difficult to kill. An easy kill (Lanc) can be killed pretty easy up to 22K, but a B26 is rough to kill at anything above about 14K.The faster bombers are much harder to get and keep position on, and coupled with the better guns are awful "salamanderly". To chase after B26's above the clouds is suicidal unless you have help (somebody else for the bombers to aim at...). Killing them alone at altitude can be done of course, but takes LOTS of patience. I've had some great fights against high bombers that took 20 minutes or more.
So I guess the decision on whether to kill bombers before or after the fighters isn't always such a simple question.
What's your in-game name Rich? I'll have to keep an eye out for you, hehe.
MtnMan