I guess Im mostly going to echo what craftydan said. There are two approaches; either you buy a beginner radio that you know you will outgrow if you stick with the hobby, or you buy a taranis and be set 'for life'.
If you go with the former approach, keep in mind that you can buy such a radio second hand, and sell it once you are done with it. That keeps the cost pretty low. As for which one; if you are planning on multirotors, Id also stay away from the 9x, the stock firmware is almost unusable for those, and upgrading it not easy at all. Exception could be if you can buy one second hand thats already modded with Er9X and possibly other mods (backlit LCD mod, audio mod, telemetry mod, .. these things get modded a lot!).
If you are planning on fixed wing aircraft, Id pick a 9x(r) over a dx6i. Some people may have had bad luck with theirs, but on mine I found the gimbals and switches actually pretty darn good, and its aged very well. I also love the fact you can plug in modules. If you want DSM2/X for bind and fly, plug it in. If you want frsky telemetry and better link reliability, go ahead. You can even plug long range UHF modules should you one day want to.
Actually, before hitting "post", I glanced over hobbykings site, and Im going to change my vote. I used to argue against the 9XR pro because it was too expensive compared to a clearly superior taranis, but the price has come down meanwhile, and at $99 (without rf module! edit: and without battery. Hmm..), it actually makes for a nice "taranis light". You'll have fulll programability almost on par with taranis, support for telemetry, speech, RF modules, USB, .. its more than you need as first radio, but at that price, Id certainly consider it.