Park tools' own is the best.
Park Tools don't specifically state it's compatible with 11 speed though:
http://www.parktool.com/product/mini-chain-brute-chain-tool-ct-5? Works on derailleur chain including 5-, 6-, 7-, 8-, 9-, and 10-speed chains
Is there any reason why a chain tool wouldn't be 11 speed friendly? (Aside from that weird 11 speed Campag stuff.)
To be quite frank, I usually use them even on 11 speed as longi got a quick link to join them up again.
I find the park tool version is the least likely to go wrong.
@edscoble started
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Park Tools don't specifically state it's compatible with 11 speed though:
Is there any reason why a chain tool wouldn't be 11 speed friendly? (Aside from that weird 11 speed Campag stuff.)