Your radio choice is partly dependent on your budget and partly dependent on what you think you'll be doing in the next 2-4 years. If you've only got $100, the choice is 4 channels. If you've only got $150, you can get a 6 channel computer radio like the 6EXA. If you can afford $200+, you can step up to a 7 channel. While you are thinking about your radio choice, consider all of the other things such as building tools and flight equipment, you will need to buy. The expenses go up quickly. I've seen some people recommend 7, and even 9, channel radios for beginners. Personally, I think MOST beginners are better off limiting their startup costs and staying with a 4 or 6 channel radio. If you outgrow it in a few years, so be it. You can sell it or keep it as a backup in case you have to send the new one in for service.

I've got a 6EXA, and I've had it for more than 6 months. I have occasionally wished for a few more features, but not enough to justify the extra $$$ to get them. If you think you might want to go with the 7 channel in the future, but can't swing it right now, go for the 4 channel and get the 7 channel on the same frequency later. You'll be able to use the flight pack from the 4 channel with the 7 channel.