Hey guys! I'm starting up a new army once I get my student loans for the summer in a couple of months. I'm torn between the tyranids and the grey knights. The tyranids look so cool, I love their background and the new models are amazing. The grey knights are likewise very cool, lots of lists work for them and they're pretty competitive right now. Any thoughts on which one I should start?

I've been out of the 40k scene for about 6 months now so I'm pretty clueless on what's good for the grey knights, except that Psybolt dreads are ridiculous. I've also heard that the Nids codex pretty much blows.

My favorite armies are Eldar and Orks if that helps. I like a good deal of finesse in my armies (I have an odd ork list that doesn't rely on numbers :P)