What are the features that you generally look for in a radio ? 

The absolute must ones, and the really nice to have ones. 

Not the exotic stuff

4-6  channels  is a basic must have with
Elevon Mixing
Flaperon Mixing
V tail Mixing
Dual rates for all control channels .
Price wise now a days the difference between 4 and 6 channel is minimal hence will go for 6 channel .

Beyond that I really don't find other functions to be of too much use in a fixed wing .

Timer is good  but not a priority , I prefer depending on my judgement of power consumption relative to time to be more than enough with electrics . In any case you can program an ESC for low voltage cutoff in case of LIPO's .

I prefer to use y connectors instead of mixing channels in case of aileron's for example .

Frankly I prefer my control rather than machine prompted controls  

Sai

My list is more frugal

4 channels
exponential
servo reverse - don't laugh - not all radios used to have them
servo travel adjustments
digital trims
model memory

anything more than above is luxury - I don't fly more than .40 size anyway

these are one of the most important ones.

v-tail mixing
dual rates
servo centering
servo reversing
Elevon Mixing
Flaperon Mixing
fail safe
must look descent 
naming your model would be nice (though not necessary)
exponential

i believe i am asking for more but these are some of the iimportant features

The features that I use in my radio are,

1. Triple Rates (Low rates, F3A rates and F3D rates)
2. Exponentials
3. Throttle Curve in Airplane mode
4. Throttle Cut
5. Idle Up / Idle Down
6. Flaperon / Spoileron / Dual Aileron Mixes
7. Timer
8. Servo Travel Adjust / Servo Reverse
9. Sub Trims
10. Fail Safe
11. Digital Trims
12. Model Memory
13. Heli programming features like Throttle Curve / Pitch Curve and switchable between normal and stunt mode for my Variable Pitch setup!!

- Chan

If you pay the money you get features. low cost = less features, higher cost = more features. 
Range of Tx to Rx is most important features i love to see.......
should use Li-Po or Li-ion instead of NiMh.

Looks like telemetry will be one of the big things coming up.

most important is range

I missed out "Trainer support" 

Full range transmitter means wats the range?

I dont think the comodity Tranmsitter sytem comes with the different Trasmitting power or 'Range'. Due to different US/EU regulation, the Tx power is limited to 300-600mW.
Yes, we do have Full range/Park Flyer/indoor Receivers which due to various lever of Rf Pre-amplification, give different range with the Transmitter.

Most of the popular Radio give enough Range of 1 - 1.6Km with their full Range receivers, enough to make a 2M Wingspan Sail Plane disappear!

More than Range, the reliability of the Tx system is important.

Thanks for the info..

Does the Dx6i have servo reversing option?

yes dx6i has servo reversing...

If a radio has no servo reversing, it is pretty much useless.  This means that even if any other feature is missing, they tend to have servo reversing, even if it is by individual physical switches for each channel.

like which types of brands which are giving 600mw

anwar bhai recently too many radios in the market i am beginner so which is good and long life

many peoples and reviws r  futaba t7c nowdays

Hey hi there,
 
                  M using http://www.dynam-rc.com/products/transmitter/2.4G-6ch.htm this radio.Is this programmable?
If not can Channel mixing be done in this.M using it for plane

Nay ! not programmable !!


PS

if 'M' is using this radio why is 'Rajesh' asking questions? what happened to 007 ?

Doesn't 'M' know SMS language is not permitted ? If 'M' doesn't stop SMS language, will tell 'Q' to give thy a 'Dild'

A SOLID ROBUST RF link is something no brand offers.
It's unfortunate that technology otherwise is progressing in leaps and bounds but none of the manufacturers seem to be even concerned about providing a more robust RF link.
its sad that no matter whether you fly a basic trainer or a 20L Jet the options are the same.
I've used only JR and Spektrum for 10 yrs and on occasion have used Futaba.
I've seen failures with both , I don't want to get into a Futaba vs JR discussion but either way the RF link is definitely something manufacturers need to look at.
The more expensive top of the range radios offer only better programming options but the basic RF link is the same as any other cheaper radio

+1
Nandan
My telemetry beyond 800 mtrs is beeps more often than not, telling me that i am loosing range & lock.

This is because radiated power and available spectrum is limited by law -it is possible to build a bullet proof rf link but then it
would be illegal.

stupid government....interfering with our hobby...

ha ha ha
hey rcpilot can i do mixing in this radio
i am not getting
how to use all these dip switches
how the function
i know only that revercing
what is PIT switch
throtal curve
exponential??