The 12S looks to be aimed more at the bench flier as it looks to impress.
I like the 10s better as it has side sliders (I love these). Also the screen takes a lot less power to run. As I often need to hike into many of the slope flying sites the weight saving is noticeable! I often swap this weight for water. The 10S comes with a Li Ion battery a big plus.
While I've had 12 channel radios since the 90’s (Multiplex, Profi 4000 and Royal Evo 12) I’ve never used all 12 channels.
If spending your own money I’d look at the Horus X10S. I think it is a much better RC TX rather than the bench jewel that is the X12S
From the Aloft sales page:
X10S
- 16 channels (32 channels when combined with an external XJT or Ranger module)
- Ball bearing gimbals equipped with Hall Effect sensors
- High Resolution TFT, Transflective Screen, visible in direct sunlight
- Antenna malfunction detection and SWR telemetry
- 2 internal antennas and one external removable antenna (can operate on either option)
- Audible Speech Alerts (values, alarms, settings, etc.)
- Safety power switch (no accidental power downs)
- Li-ion battery pack
- 6 position encoder
- FrSky FrTX OS
- Option to install OpenTX
- Protected Internal Antennas
- JR Style Module Bay (to expand you RF options)
- Full Telemetry · RSSI indication and alarms
- USB and SD card slot for system expansion
- Data Logging
- Trainer Port
X12S
- 16 channels (32 channels when combined with an external XJT module)
- CNC Aluminum - 6 ball bearing, gimbals equipped with hall effect sensors
- High Resolution TFT, Transflective Screen, visible in direct sunlight
- Antenna malfunction detection and SWR telemetry
- Audible Speech Alerts (values, alarms, settings, etc.)
- Safety power switch cover with integrated strap attachment point
- Two types of trainer ports
- 6 position encoder
- MP3 Player
- FrSky FrTX OS
- Option to install OpenTX OS
- Stereo Speakers
- Protected Internal Antenna
- Internal GPS
- JR Style Module Bay
- 16MB on Board Flash Memory
- Full Telemetry · RSSI indication and alarms
- USB and SD card slot for system expansion
- Data Logging
Disclaimer; I don't own ether.
All the best,
Konrad