The Tyranids have been my army of choice since Rogue Trader. With the 5th edition out they have a few units that aren’t represented by models yet. Notably the Tyrannofex, Tervigon, Harpy, Doom of Malan’tai and Mycetic Spore.
I’ve come across a few sites that offer modeling suggestions for these (Tyrannofex and Tervigon) – most built around a Carnifex frame. With the bits I’ve been getting online, I’m looking forward to giving a few of these a try.
The first one will probably be a Mycetic Spore. I’ve picked up some of the large Kinder eggs to use. Back in Second edition, I had made a bunch of Ork adobe buildings and a few craters with the large Kinder eggs in them – sort of an alien drop pod. They will work nicely to start with.