I was very happy when I started with my rasp3. It’s perfect for openhab and it has a power consumption near the zero 
However after a year of use I can see its limitation (the same you can read everywhere): first big issue I had it was the breaking of mmc, after I bought a good quality mmc and all it’s ok.
Second limitation is the small quantity of ram, from OH2.5 I’m near the full and I’d like to install a DB instance, graphana and a small instance of nextcloud. Now I don’t know if is better an upgrade with a rasp4 or better a nuc. Now the CPU is ever near the 2%, so I don’t think a nuc will give me a performance increase and the power consumption of the nuc is not trascurable
