Playful:
* EN-G (emphasizes the language element)
* E-LISH (shortens the word)
* ENG (classic, but a bit bland)
More absurd:
* E-N-G-L-I-S-H (overly long, emphasizes the letters)
* E.N.G. (formal but silly)
* E-N-G-L-A-N-D (plays on the association with the country)
It really depends on the context! Is this for a school project, a joke between friends, or something else? The best abbreviation will be the one that fits the situation and your personal sense of humor.