I am into trading since a few years, and I have been experimenting with many different crypto exchanges which use Bitcoin as "trading unit" and allow to trade many different assets and currencies.
This is one of the main exchanges, the biggest one for the BTC/EUR pair.
I've been trading a little using it, but there are some cons:
not easy to understand the effective P/L (profit/loss) before closing the position
not very high leverage
So, probably, the best way to use Kraken is just to exchange BTC into EUR and move them to your bank account easily.
Poloniex
This exchange allows margin trading and leverage, but with the following cons:
you need to put some BTCs into a separate account, which will "fund" your margin / leverage trading
understanding how the whole system works is really, really difficult, and you often end up with a big confusion
There are some pros, too:
countless cryptocurrencies to trade
lending system
1Broker
This is one of my favorite exchange, you can start with 0.01 BTC and the trading system is quite straightforward and easy to understand.
There are other pros:
you can trade traditional stocks, forex, commodities and indexes
you can use the ultra-cool feature of the social trading, which allows to "copy" the best performing traders
The only con is:
no way to trade BTCs or other cryptos anymore (they're moving the crypto trading to a new website, still under construction)
I've not been able to test this website, because it requires (as far as I know) at least 0.34 BTCs to live trade (otherwise you can only use a demo account).
The website and charts are very professional and full of features, you can subscribe here: SimpleFx website with my referral in it
Bitmex
This is quite new to me, and I'm starting to use it recently.
It has many features and works very well, but there are some cons too:
very complex system, you need to learn how it works before putting too much money into it
not so many cryptos to trade at the moment
The cons are very interesting:
the charts are provided by Tradingview and you can add as many indicators as you want (different from the Tradingview free account, where you have very limited indicators available)
the website gives a really great user experience, and everything is very well documented (even if you still need to learn many details to fully understand and benefit from the system)
@andrew0