Yes it is a Ford vs.Chevy question!  LOL

Get as many channels as you can afford.  If I had to choose between your choices, I'd go with the 8 channel.

Also, see what other people at your field are using, because no matter what brand, the manuals leave a little something to be desired.  They'll be able to help you with set ups and little "tricks" they have learned.

Personally I have a 7 channel Futaba, but I know many people with Specktrum and Airtronics radios that have no real negatives about them either.  I got a Futaba because almost all of the other people I fly with use Futaba.

I would also suggest seeing if you can get a couple in your hand.....flying is difficult enough.  Don't compound it by getting a radio where you can't reach the switches, etc. without looking.