Idioms that mean making decision between two good options

I am looking for expressions that mean "to decide between two good options." For example, you have to choose between getting a car that you like or a super car that's very expensive but you are not sure if you like it.

I searched on Google and there are some phrases that mean to make decision between two unpleasant options so, I am not sure if there such an expression in English or not.

Not quite the noun you are after, but another way to express the situation is to say that you are spoilt for choice

This is an approach-approach conflict:

http://www.merriam-webster.com/medical/approach-approach%20conflict

a psychological conflict that results when a choice must be made between two desirable alternatives

Best illustrated by Rebecca Black:

http://www.funnyordie.com/videos/6c4e44a1af/which-seat-should-i-take-w-rebecca-black

Front seat or back seat? Which one should I take?

As you note, the more common conflict is the "avoid-avoid conflict" where you must choose the less bad of two bad alternatives, and the "approach-avoid conflict", where there are simultaneously good and bad aspects to the conflict.

The psychological condition of having too many good alternatives to choose from and no ability to decide which is best so you choose none of them is option block, coined by Douglas Coupland in the novel "Microserfs", though that doesn't seem to have caught on. Overchoice is another option, coined in 1970:

http://en.wikipedia.org/wiki/Overchoice

When confronted with a plethora of choices without perfect information, many people prefer to make no choice at all, even if making a choice would lead to a better outcome.