Are Nickel plated chains more resistant to corrosion and are they easier to keep clean? They are certainly more expensive. What about brands? I like SRAM due to the quick link.

While plated chains look nicer, I feel corrosion protection is more related to the lubrication on the chain. The act of lubing and wiping off the excess lube spreads a protective layer on the chain. SRAM makes a great chain, but same could be said for any of the other major manufacturers (Shimano, Wipperman, KMC...). I've used mainly SRAM and just starting to use KMC chains. I've never been a fan of Shimano chains, mainly because of the requirement to use a new pin.

SRAM's Powerlink masterlink on the 8 & 9 spd chains are easily removed and installed by hand, and can be used multiple times. However, SRAMs Powerlock on the 10 spd chain is intended to be a one-time use masterlink and cannot be removed with the fingers. KMC sells a finger friendly and reusable maserlink on their 10 spd chains.