Plenty of options for this one. All of the following can be made to sound snarky if said with a sarcastic tone, but none of them carry an inherent negative connotation.

> It's up to you. OR I'll leave it up to you.
>
> It's your call.
>
> I'll let you decide.
>
> Let me know what you prefer.
>
> It's up to your discretion.
>
> You're free to choose.

...and more.

The choice between these depends a little bit on context. If you're trying to convey that you want them to choose, but that you don't need a say in the choice, I'd personally choose "Let me know what you prefer," because I want to stay in the loop.

If, on the other hand, I'm trying to say "I don't care what you do" in a polite way (simply saying that I'm not affected by the choice), I'd lean toward "It's up to you."

Again, it depends on the situation, so when deciding which to use, *it's up to you.* ;)