Other than
@Ebeneezer Goode popping in with a good old ‘keep it simple’ with PMR, most have gone straight in with the pros&cons of licenced systems
Nobody has asked what
@Halointends to do with a radio.
Is it for general airsoft use, talking to anyone on the same side ?
Is it for talking to only a team group?
Is it within a reasonable range in the woods, indoors, an urban area?
The best answer for general use is standard PMR, any model, by any manufacturer. Just UK compliant, on PMR frequencies and within the power range with a fixed aerial.
The common answer is a fully programmable radio, usually Baofeng, supposed to be operated with a licence and programmed to PMR frequencies illegally operating over authorised power levels
A good point is that most posters have pointed out the need for a licence if doing so.
Ive used many, sometimes licenced, mostly standard PMR.
The ‘best’ handset I have used which gave me great value for money with the ability to monitor comms across multiple ‘channels’ was a cheap and nasty Tesco PMR handset operating on the original 8 analogue PMR frequencies without the sub and did not ‘support’ the sub frequencies. But due to that lack of support I could set it to the basic home frequencies and listen to every sub frequency.
eg I was tuned to 1.00 and could only transmit on 1.00, but I could hear 1.01, 1.02, etc
Then with the aid of a fully featured PMR I could talk back to anyone
Wheh running a game I would carry a minimum of 2, most likely 3 handsets
1) Tescos cheapie - monitoring
2) Full PMR - transmit/receive
3) PMR or licenced handset - event running
Ive had a few handsets due over the years, the Tesco ones still worked the last time I tried, I assume they won’t manage to pickup my 16 channel digital PMRs - but Ive never tried