From a technology perspective zk-snarks is more private than RingCT is. I'm not saying Z-cash is better, I am saying zk-SNARKS are better than RingCT. FCMP++ would make their privacy at similar levels then Monero would be the obvious winner without a doubt. But right now, their tradeoffs, and privacy benefits are similar. I personally use Bitcoin, Monero, and Z-cash, as well as other payment types when I have to. I'm a multi-coiner but I prefer, Bitcoin, Monero, and Z-cash the most out of the three, as I see they have the most plausible real world utility currently.