So if you go HP2551 and Ecowitt then you can have the individual primary external sensors (anemometer, Hygro/temp, Solar, wind direction and Rain gauge) or the traditional all in one sensor. On top of that you can add soil Moisture (not temp yet) and a Air Quality sensor that measures PM2.5. You can also add extra internal thermos/hygro sensors for internal rooms (up to
Ecowitt/FO are working on a lightning detector but no timescales and soil temp sensor has been discussed but nothing firm.
Ecowitt are much more flexible and if you open dialogue with Lucy you can usually customise whatever you want order wise.
If you prefer Ambient then you are locked into their ecosystem and what they sell and in those configurations. So for instance you can only get the WS-2000 with the all in one sensor array and the additional sensors it sells.
There are pro's and cons as discussed on the forum.