Good luck with getting into the UAVs ahead of all! That’s a strong motivation for jumping into the surveying material
I believe I have some details to help you make an informed decision. Even though for me Reach RS+ is always good enough
When talking about the choice between the units, it all comes down to the environment you’re surveying in. If you can always provide the unit with good satellite visibility and a clear sky view so that nothing blocks it, single-band receives are for you to go with. Reach RS+ can be easily put either on the tripod or on the surveying pole.
If your environments are complicated and have diversity, you may want to go for multi-band receivers. They are robust in challenging conditions like the city or the slight foliage. In this way, you’d want to look at the Reach RS2. More expensive, true, but unavoidable in case of complications of the environment.
As @jp-drain-sol mentioned, you can go with the multi-band Reach M2. Unlike both RS2 and RS+, it’s a bit trickier to place on the pole and on the tripod: it doesn’t have the thread. There are several external components as well, like the battery and the GNSS antenna. Still, if the idea of placing this on a tripod doesn’t scare you, M2 will work just as well as RS2.
A quick trick for you: if you have access to the somewhat affordable NTRIP services nearby, there’s no need for two units. You can connect just one to the Internet and survey with it. This is one of the ways we do the GCPs collection in our guide. This option, however, needs to be weighed against all costs.