Sony 16-50 2.8 versus CZ 16-35 2.8

I have narrowed down my choice to purchase one of these. The CZ to future proof moving to FF (no FF yet, but have 4 APS-C). Has anyone got both? Is the CZ worth the extra money and IQ? Or does the 16-50 perform close to the CZ?

I want to avoid having to upgrade yet again later (getting tired of buying and stepping up), but also mindful of my heavy use of APS-C right now.