LX has a nicer hard product.

OS is a draw for soft product and has better catering.

Personally I would choose whichever flight is direct given that JFK is a fairly short flight overall.

If departing from Vienna OS.

From Zurich/GVA LX.

If lounges are a big deal to you LX has nicer and less crowded lounges in ZRH than OS does in VIE.