Kraken offers great volume, responsive customer support and many advanced trading features. My review left me with some technical concerns and it sounds like I'm not the only one. If you're just starting out with trading cryptocurrencies, maybe start with a more beginner-friendly platform.
Initially, I was excited to use Poloniex because of the great variety of trading pairs. Getting verified and buying some altcoins was a straightforward process and I preferred the user interface over several other exchanges. However, after submitting a customer support request and never hearing back, I started to understand why users question the legitimacy of the exchange on social media.