Karnak, I don’t want to knock the Spit, I’m kinda a closet Spit lover myself.

The G6, as I amended in my edit, was outperformed slightly by the LF.IX (about 7mph in speed, however the G6 was slightly superior between 16k and 20k). The 109G series actually started production in 1942, and the G5 had MW50 boost and was a more pure fighter than the G6 and didn’t have the G6’s fanzy armament options and heavy armor. However in 1943 Germany needed bomber interceptors so the G6 was produced in far greater numbers than the G5. Not many spits over Germany remember.

The Spit XIV is a 1944 model that match up to the G10 pretty well, not that they saw much combat with each other in WWII, the Spit XIV did however shoot down a lot of doodlebugs. Only 957 Spit XIV were made.
One on one any Spit is a deadly opponent, however in multi plane fights acceleration, climb rate and top speed are the important factors. All our historical setups in AH show this. In the 1942 N. Africa TOD the 109F4 were like Tempests compared to the slower Spit V’s, and when a squad of Spit V’s can do nothing but turn to avoid attacks the squad of 109F4’s will dictate the fight.
I primarily fly the 109F4 in the MA, and I have no problem fighting Spit IX’s with it. The 109F4 isn’t more manoeuvrable, it isn’t much faster (10mph or so at low alts, superiority goes to the Spit at high alts), however the 109F4 out climbs the Spit IX, and that’s the killer in an E fight.
I would prolly fly the 109G2 if not for the Finnish markings that make it so easily identified. The 109G2 is almost as powerful as the G10 in pure horsepower climbing (again lacking the heavy armaments and armour of a bomber interceptor). And in a co-alt E fight climbing power is the killer. However if the Spit (any Spit) has alt on me I’m having a bad day (no wonder the 109 pilots always climbed to their service ceiling before engaging

)
I’ll give you this Karnak, the Spit IX is what I consider one of the most dangerous opponents in the MA in the hands of a good pilot. Not because it has superior performance, but because it hides energy so well, and it has those hizookas. Make one miscalculation and the Spit gets an opportunity to kill you.
To summarize:
109E4 vs. Spit I. 109 is superior (historically, dunno about AH though. I know there are issues with the roll rates of these two planes in AH).
109F4 vs. Spit V. 109 is superior.
109G2 vs. Spit IX. 109 is superior.
109G5 vs. Spit LF.IX. 109 is superior (I think).
109G6 vs. Spit LF.IX. Spit is superior.
109G10 vs. Spit XIV. I would say parity judged from the late war special events setups.