I'll throw my $0.02 in as well, but I'll say that if you have a chance to get your hands on the radios first, DO IT.
When I bought my transmitter a year ago, I bought a Spektrum DX6. I was able to pick it up, feel where all of the buttons and switches were, and see how it felt. Ergonomically, the DX6 felt the best to me. In addition, when I looked at the Taranis that was $50 cheaper, I started moving the sticks around and they felt mushy to me. I made mention of that to the person at the hobby shop, and he said, "Well, you can swap them out to different gimbals, but it'll be $50 for the upgraded parts."
Since that put me at the Spektrum's price, AND since I had a lot of people flying Spektrums in my area, AND my particular quad that I was looking at already had a Spektrum receiver in it, I just went ahead and spent the money on the Spektrum DX6. Dpes that mean that you need to fly with the Spektrum? No...But I would highly recommend finding something that you like the feel of before you drop the money. Remember, you're going to be holding that thing the entire time you fly with it; if it's not comfortable, you're not going to want to keep flying for a long time, and if you're using switches that aren't ergonomic (which has happened to me with an older Graupner controller, as well as an old HiTec radio), your hands are going to cramp, and it will NOT be a fun flying experience.
That's something that I recommend REGARDLESS of your radio choice - find something that's comfy, if you can. They're all fairly similar, but not all are comfortable.
Last thing that's a REALLY nice feature with the DX6, DX8, and DX8e, and I think the Taranis and some others like the Graupners have this - the voice features. I have with my radio, the ability for it to tell me how much time I have left in certain increments. It's nice to hear it tell me, "One Minute" or "30 Seconds remaining" when I get close; that way, I know I need to start planning to land within that time.