That depends on whether you plan to climb up and chase fleeing bombers, or if you're prepared to take off, climb in advance, and *then* hunt the bombers down.
Patrol:
It's a toss-up between the 190-A8 with 2x30mm and the P-47N. They both have a great balance of firepower, performance, and range. Any good player can kill bombers in any aircraft he knows well. If that player spent his time in those two aircraft he would get
slightly more bomber kills. Climb to 20k in each and you have ample range and enough performance to chase down any of the light heavies, moreso in the P-47N. If they're below you, smile, if they're at 25K just climb a bit. The 190-A8's firepower is enough to down a bomber with one quick pass, e.g. this Lancaster, which is in trouble:
You don't have to be a particularly good shot; just dive down on them, hammer them, gently pull out and do a corkscrew around them. Your first kill is free, your second kill is only slightly harder. From that point on you'll be low on energy but you'll only be fighting one bomber. Take your time. The two aircraft have a mixture of strengths and weaknesses. If you get hit in the 190-A8 you'll probably end up with the oil out rather than a main tank leak or a pilot wound; in the P-47N you'll get the main tank shot out. In both cases you have at least a chance of gliding home. The P-47N is much stronger against enemy fighters but the guns are such that you have to
aim, if only for a split-second.
All the other choices are generally suboptimal. The 109K4 is a very close third, the only limitation is the firepower, which is good but not great. The 110G2 has less firepower than the 190-A8 in its stock form, and doesn't perform as well. In particular it's rubbish in high-speed dives. It's a big target and everybody wants to kill you. The extra gun package cuts your performance and doesn't really add to your killing power; you can only kill the bomber so much before more bullets are a waste. If you're up against a flight of two hundred unescorted B-17s and the gunners are away from the keyboard, go for it. Ditto the 410, which if anything seems even worse in a dive, and more fragile. The Mosquito has a tremendous gun package but in my experience you get lots of pilot wounds; the Typhoon also has great guns but has a glass radiator and very short range. The N1K2 has the firepower but doesn't perform as well as the 190-A8. Everything else either has less firepower or less performance or less range. The G14 with gondolas has almost the firepower of the 190-A8, but on a personal level I prefer the 190's roll rate and its handling in a dive.
The Ta-152 is an odd cross between the 190-A8 (similar firepower) and the P-47N (range, performance at high altitude), and one of those big fat disabled women who rides around in an electric wheelchair. In my experience the A8's extra 30mm and machine guns ensure a one-pass kill, with the Ta-152 it's not quite as assured, and the longer you spend on the attack the harder it gets.
I'm not counting the 262, which is of course superb against bombers if you can hit them without running into them.
Chase:
BF-109K4, easy. Terrific rate of climb, excellent performance, sufficient firepower, endurance, magic WEP. In my experience the single 30mm does enough damage that if you land hits but don't manage to finish the bomber off, then if somebody else shoots them down
you get the kill, because you filled the bomber with warm human jam.
On a tangent, and I'm not a mathematician, but my hunch is that if the bombers are coming straight towards the base at 20k, 270mph+, and you spot them on the edge of the radar circle, then only the Me 163 has a hope of climbing to shoot them down before they drop their bombs. I imagine you could draw a chart which shows the relative merits of altitude and speed - I suspect that a formation of Bostons heading for the target at 12k, 325mph, would be just as safe from interception as a formation of B-17s coming in at 20k, 280mph, for example. In any case you're vastly more likely to be chasing after bombers that have already attacked, in which case I've always wondered why more bomber pilots don't simply ditch; it lets you double your sortie rate (you don't have to fly back) and really angers the defenders.
