Xs.com is the leader of the industry personally for me and I can easily break it down.
i. Registration was seamless, without any difficulties, even though I can't brag about vast prior experience. Just a couple of months of clicking buy/sell with another broker without any understanding what position size meant, margin trading and all that. So, getting back to registration - intuitive procedure.
ii. Opening an account, switching between demo and real one - just a pleasure. Seriously, it's also very fast and is done within few clicks. I traded on the demo, was passing some courses to get basic knowledge, checked their blog and i am on the real one.
iii. Conditions. As far as I can judge, they are suitable. Leverage up to 1:2000 and MetaTrader platform do wonders, for real...