Small Scale Military Headquarters

Ok, I'm a novice when it comes to aircraft. I'm shopping for a German 109 European Theater fighter plane.

What is the difference between the ME-109E-4, BF-109G-6, and BF-109G-2 and which would be best suited for the European theater?

This should answer your basic question:
http://en.wikipedia.org/wiki/Bf_109. An aircraft reference book may also be helpful.

However, without being too technical, there are several basic differences between the E and G series Bf-109.

Armament:
There was a change in armaments between the two series. The E version had two 7.92mm MGs in the nose and two 20mm cannon in the wings. It could carry a droptank or bomb. The G2 had two 7.92mm guns in the cowling and one 20mm cannon in the prop spinner. The G6 had two 13mm MGs in the cowling, a 20mm (or 30mm) gun in the spinner and provisions for two additional wing-mounted 20mm cannon, in addition to a variety of other armament packages. The G series planes also carried centerline droptanks or bombs.

Wing Shape:
Between the E and G series, the wing shape also changed: The wing on the E series has a more angular appearance with flat wing tips; the guns were mounted internally in the wings. The wing on the G series planes was actually shorter and had a rounded tip. Both series had leading-edge slats. Guns were not mounted internally on the G series wings.

Fuselage Shape & Powerplant:
The fuselage shape also changed between the E and G series planes. The change actually first occurred with the F series of the Bf-109. This was because the engines were upgraded from a DB-601A on the E series to the DB-601E on the F series and finally the DB605 on the G. This engine change necessitated a reshaping of the fuselage and it was made more streamlined. There are also canopy differences. The E series had an angular squared design; the G series kept the same basic shape, but the canopy framing was heavier so the cockpit could be pressurized. Struts on the horizontal stabilizers of the ME-109E were removed on later Bf-109 models.

There are also a number of other smaller differences that I won't get into here to save space. The wikipedia article should answer most of your questions as it seems rather extensive.

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All variants will work well in an ETO theater setup. For clarity, I'm counting the Russian and Italian fronts as part of the ETO.

The ME-109E series plane works best for an early war dio. Some of the 21c versions such as the original "White 12" or the "Galland" planes go well with the Spitfire and green Stukas. The tropical ME-109E goes with the RAF P-40 and desert Stukas; the winter ME-109E with the winter Stuka.

The G2 will work best for a mid-war setup. The BBI version in the DAK colors will go well with the 21c RAF P-40 and desert Stukas. If repainted in ETO colors, it will go with the P-38 and P-47 razorback.

The G6 was the most-produced variant of the Bf-109, so it would be the most logical choice for a general ETO setup. The 21c Bf-109G6s all come in ETO theater cammo schemes. Basically, a similar variation of dark gray and green splotches on a light gray/blue undercoat. These planes will go well with all the 21c mid to late war ETO planes including the FW-190D, ME-262, P-38, P-47 razorback & bubbletop, and the P-51D.

So, given that I have too much time on my hand at the moment, that is the 1:18 scale Bf-109 rundown. If you are hell-bent on an ETO setup, then the 21c Bf-109G6 would be your best bet. It is one of my personal favorites in 1:18 scale. I'm sure BBI will eventually make an ETO repaint of their Bf-109G2, but that could be a while...

Hope all this helps

The biggest difference (naturally) is going to be the time period you wish to model. The "Emil" (E model) was most noteable for it's use during the Battle of Britain earlier in the war. The "Gustov" mated a more powerful engine and ungraded weapons to the same basic aiframe. Biggest difference between the G-2 and G-6 were bulges just in front of the windscreen to accomidate the ejector chutes under the upper cowl for the above-engine guns. There are ALOT of other minor alterations, but those are the most visible ones. All three served the European areas as well as the Med, Africa, and Russian fronts.

An even more important note is this:

The Emil was a first generation mold from 21C and it is MUCH less detailed than the updated Gustav tooling. Trust me on this, you want the G model unless there is an E paint scheme you just have to have.