Very interesting topic. You guys got me thinking and i think i can offer another perspective that deals with some distinctions in the comparison.
First of all, saying that X is the better fighter is a bit too vague. For example, a more accurate question would be "better in what and under what circumstances"?
Comparing only technical data is too narrow a point of view, adding tactical application of the airframe is a bit better (as the relative performance dictates the optimal fighting style) but then again it's useful for comparing aircraft on the basis of a 1 on 1 duel. This rarely happens in actual combat.
Things like pilot training in the proper application of the aicraft, as well as peripheral factors that influence combat can play a big role in the final outcome.
I do think the 109 was the better fighter when speaking from a purely technical point of view, plus it had some of the most experienced pilots at the time flying it. The reasons it couldn't turn the tide are the host of peripheral factors that influenced the way its sorties were flown and most of all, the inter-dependent dynamics between different types of friendly and hostile aircraft.
What i mean by this is something that many virtual pilots, especially those who fly the 190, can understand. A fighter is not strictly a boom and zoomer or a turn and burner, it depends on the opposition. The same fighter is a boom and zoomer when used against something like an I-16, but it's a turn and burner when used against something like a P-51. If the target is slower or turns better you BnZ, if he's faster and flies higher you rely on angles and try to drag him lower. In this sense the early 109s, while not a dog of an airplane, were mostly BnZ fighters for most of the early part of the war, as they usually faced opposition that was slower but had a tighter turning radius.
The thing is, a boom and zoom fighter (or more accurately, the BnZ application of it) which is superior on freijagd missions confines you to a certain fighting style: observing, controlling the engagement and swooping in for the kill when the time is right. You can do almost none of that when you're strapped to a formation of bombers as close escort. This is why a lot of the Russian fighters were turn and burners, they wanted them to stay glued to the bombers and gain angles fast enough to shoot down or drive away the attackers, not rack up the absolute maximum kill to death ratio.
The reason boom and zoom fighters worked well for the US as escorts during the latter years is that the German interceptors were similar in nature but inferior in performance at the altitudes the bombers operated. Well, the 109 did well up high, but it lacked the armament to consistently and efficiently be used as pure bomber hunter. The 190s were well armed and durable but lacked the performance to evade the escorts and that goes double so for twin engined heavy fighters like the 110. It's no wonder that most of the times the 109s were sent to tackle the escort while the 190s and 110s set to work on the bombers.
Back on the topic of BoB, let's combine the 109s boom and zoom nature when compared to the Hurricane and Spitfire, with the 109's limited endurance. It becomes quite clear that the 109, despite being the better fighter on a one-on-one basis, was all too often forced to fight in a way that, while not entirely favoring the opponent (the still lightweight E model compared to later 109s, while it was no Spitfire, could hold its own in a turning contest, it just wasn't the optimal thing to do), was effectively sapping it of its most important attribute in the relative match-up: the ability to control the engagement and decide when to strike.
You can't afford taking your time waiting for the best moment when your bombers are under attack or you know you have 5 minutes worth of fuel remaining in the combat zone, you just get in the fray right there and now.
Finally, the irony of it all, the armaments. Absolute optimal conditions can almost never be observed in actual air combat and aircraft design tends to account for that.
When you need to score hits on a fighter, you want to maximize the amount of rounds you can launch at the target. Generally speaking, fighters of the time were relatively lightweight and didn't take a tremendous amount of punishment to bring down, so design tended to favor batteries of fast firing machine guns as the prime anti-fighter weapon: more rounds per minute, more ammunition, easier to account for wasted ammo when leading a wildly maneuvering target by tracer or executing a tracking shot.
On the other hand when the intended target is a bomber, you want to maximize the amount of destructive power per projectile in order to limit the amount of time your fighter will spend within the bomber's defensive fire arc and range. The bomber doesn't maneuver that hard, it's easier to score hits on it, so all we care about is making each hit count the most. We don't care if during the firing pass the cannon spits half the amount of rounds a machine gun can, because we get a higher hit percentage due to the target's sluggishness and our rounds explode. Explosions on aircraft loaded with fuel and bombs really are a big deal after all. Hence, the preference of cannons as anti-bomber armaments.
Well, in the actual battle things were ironically reversed.The 109 went on to escort bombers and fend off some of the most nimble fighters of the time while armed with slow firing cannons that held a magazine of just 60 rounds. On the other hand, the RAF fighters intercepted bombers day in and day out while armed with a more or less strictly anti-fighter weapon system. One that due to its lightweight projectiles required a very strict observance of concentrating hits in one point to have any effect, something that meant the pilot had to spent more time within the bomber's defensive fire to have any chance of doing meaninfgul damage.
I bet that it wasn't only Galland who wanted a "squadron of Spitfires" to win the battle, but many British airmen would have also liked to have a squadron of 109s to use in bomber busting
