So, bought a couple of beam too!  I had to consider wheter I should choose beam or grin as well, but in the end, I decided to buy beam- grin simply will have a much higher inflation rate in the first few years.
And my favourite exchange for trading beam is chainrift- only little volume- but I heard too much negative reviews about many other exchanges that offer the beam coin... chainrift has the best reviews there! There are especially big concerns about security or even scam going on on some exchanges with- of course- bigger volume than chainrift....