I have an 1/48 Eduard Weekend Edition Bf109E-3. Being a Weekend Edition it has one decal/color scheme. I am not one to do the usual stuff, so I would like to do something a little different.

Can anyone point me to some decal sets that might offer some good alternatives to the norm?

My proposal are decals from Kagero books (Miniatury Lotnicze/Air miniatures or Monografie/Monographs series).
This is my Bf-109E-3 with Kagero's Air Miniatures No 2 "JG 26 „Schlageter” vol. I" decals.

Maybe the Japanese Me 109. I think they were based on the E-3 but may have been an E-7.

Or maybe the captured 109 E-3 with RAF markings?

The Japanese one was an E-7, however, there's lots of other choices, including:
Romanian, Bulgarian, Yugoslavian, captured French Air Force and Switzerland.

https://www.ebay.com/p/667606708

You may find some inspiration here.