KYC with INGTrade (ing-trade.com) is a nightmare. I submitted my ID and proof of address. They rejected it and asked for a utility bill. I sent it. They asked for a bank statement. Then they asked for a selfie with the ID. Then they said the selfie did not match. I gave up.
Pros: Full transparency|Competitive fees|Intuitive for beginners
Cons: Slow to add new assets|Spreads widen during volatile periods