Probably the most asked question on these forums is which Devo TX to buy. There is no one-size-fits-all answer to this, but I will give my personal opinions on the matter here.

The Devo7e can be had for $50-$80 US. That puts it in the same price range as a Turnigy 9X.

• Pros:
  • cheap
  • bright screen
  • small, light weight

• Cons:
  • only 7mW output power
  • only two 2-position switches
  • gimbals are inferior to its bigger brethren
  • limited memory means some features can't be supported (no multi-language support)

In my opinion, I would only buy a 7e if I was planning to primarily fly micro-helis, and wasn't big into lots of 3D trick flying.

Initial note: I don't actually own a Devo6, so my experience is limited to the short time I've used one during development/testing. The Devo6s has the same shell as the Devo7e, and runs ~$150US. It has a color touch screen (generally considered to have better contrast than the Devo8). It has 2 additional 3-position switches compared to the Devo7e. Internally it is basically identical to a Devo8s with 2-fewer 2-position switches. It is a good transmitter, but I think a Devo10 at the same price-point is a better deal.

The Devo8S is usually priced around $200 US.

• Pros:
  • color touch screen
  • four 2-position switches and two 3-position switches
  • two additional trims can be used as analog controls
  • high-quality gimbals
  • ~100mW output power

• Cons:
  • the screen can be difficult to read in direct sunlight
  • the touch-screen in not particularly accurate

I think this transmitter is a great deal for the money. The color screen is pretty, and enables a nicer user interface. Quality is generally good. The radio is not too heavy, and balances nicely on a neck-strap. I do almost all of my development using this radio. If you don't expect to need quick-access to additional analog controls, this radio has everything you are likely to need, and I definitely recommend it as a solid buy.

The Devo10 is usually priced around $150US.

• Pros:
  • very good contrast is easy to read in all environments
  • like the Devo8, the Devo10 has four 2-position switches and two 3-position switches
  • two additional trims can be used as analog controls
  • high-quality gimbals
  • ~100mW output power
  • additionally there are two analog dials

• Cons:
  • with 8 batteries, it is the heaviest Devo Tx
  • I don't particularly like the button controls
  • the menus are slower to navigate without a touch interface
  • it is not possible to convey information as quickly with the b/w screen

For the money, I think the Devo10 has the best price/performance ratio of any of the Devo radios. If I had to choose between the Devo8 and the Devo10, it is a hard choice. I'd probably take the Devo8, but only because it is prettier.

The Devo12s is a beast of a radio. It runs $400-$500 US.

• Pros:
  • the screen is huge and beautiful
  • it is actually lighter than the Devo10
  • it has better build-quality than any of the other radios (and the others are not badly designed)
  • the radio has 6 additional analog controls (besides the sticks), five 3-postion switches, three 2-position switches, and 2 digital trims (besides those assigned to the sticks)
  • the screen is higher resoluton than that of the Devo8 and has much better contrast

• Cons:
  • it is twice the cost of the Devo8

The Devo12 is the Rolls-Royce of Walkera radios. Compared to radios from other companies, I don't think you can beat it for the price, but it is also much more than most people will ever need in a transmitter.

It is hard to beat Walkera's lineup for the price. The Turnigy9x with er9x is probably a better value if you want to solder a bunch of modules into it, but a Walkera Tx running Deviation supports a lot more protocols without needing to modify the transmitter other than a reversible firmware flash. The one issue I have with Walkera is their quality-control. All of the Walkera transmitters I own are well built and reliable, but other folks have gotten lemons. I think Walkera standalone Rx are overpriced and feature limited and my RX1202 is very frustrating, but those embedded in helis seem to be much better overall.

All that said, I definitely recommend the Walkera Devo line of transmitters.