best wide angle lens for landscape

I have a NEX 7 with the kit lens.  I am looking for a really good landscape lens -could be prime or zoom.  Is the Zeiss 24mm lens considered the best or is there something better.   I don't mind waiting if there is something new coming up.  I believe there is a 10-18 zoom but I'm not sure it is very good.

Thanks,

Marsha