I am sure that you guys get this question a lot. I am thinking of buying an SDR. Where do I start? I am mainly interest in VHF/UHF & 800 MHz. I like having the ability to decode various digital modes, including APCO P25, DMR, YSF, etc. Should I look at an AirSpy, an SDRplay RSP2pro, or something else?
I have an Airspy, SDRPlay RSP2 Pro, several different RTL-SDR dongles (and other radios), and other SDR radios. Why so many of these, I compare and use what I like best. I get asked this a lot and here is what I tell them.
If you are only interested in VHF/UHF, search for new things of interest, and are serious about it, I recommend Airspy. That is what I mostly use. But if you also want HF, then SDRPlay may be the better choice rather than having to use a Spyverter or other converter with the Airspy or and RTL-SDR. But if you are not sure you are serious and are not sure you want to spend over $100, buy an RTL-SDR dongle (or rather 2 of them). They will not work as well as the Airspy or SDRPlay but are still a bargain and will let you know if you want better. Note there is some software for doing particular tasks that one of the RTL-SDR dongles can do and the others cannot due to software that for some make them .
You mention 800 MHz, you will need more than one device for trunking and the cheap dongles are probably good enough for that if your signals are reasonably strong and much cheaper than 2 Airspy or two SDRPlay.
So there is not a clear answer up front until you narrow down what you will use them for and how much you want to spend--and that may not be able to say yet and may change. May be you should now buy 2 RTL-SDR dongles but realize if you want better performance or HF, you need to get an Airspy or SDRPlay.
Also, I hope you know that to decode those visible voice modes, download VBcable (which is free and I believe better than VAC which I have also used) to send the audio from the SDR to DSD+.
I suspect you may eventually end up with 2 RTL-SDR dongles and an Airspy or SDRPlay.