RB 1800's installed correctly will not stick if newer than 15 years. The older one the wiper seal was made of a different material that appears to degrade and they will leak and stick pretty common, I just usally replace the cap on them and good to go. I see more Hunters leaking from the wiper seal than anything, but the majority of Hunter in my market area is installed by crews who do not care nor know any better. I have been experiencing RB caps loosing. I have mainly seen this on 12" but I belive thats because they are in beds and left a few inch above ground to where it is visible. If I were to dig up a lot of my 4" I would suspect some leaking caps from them too. I have been instructing my guys when they thread the barbs in, to ensure the cap in screwed down tight. Bottom line, both are a comparable product and if RB did a test video the tables would probally be turned.
CIC, CLIA, EPA WaterSense Partner. And working on my CID