Having ridden 4 shocks on my HD (RP23 (2012 and 2011), zocchi WC coil, DXH air, and RS Monarch Plus), I can safely say (for my riding style) that I went with the Rockshox Monarch Plus and had it PUSH tuned, and it’s simply excellent now. VERY tunable, very plush, great spring curve for the HD.
Check out the HD thread on mtbr.com and you’ll see MANY riders agree. It cost a few quid, but now I don’t need to faff with changing the RP23 over to the coil when I want to change from trail riding to more DH stuff, as it copes with both beautifully if you set it up accordingly (2 minute job)
In answer to another query re zocchi 55’s working well… I’ve just bought a second pair of 55 RC3 Ti’s, this time with the tapered steerer, and sold the previous pair, which had worked flawlessly after many pretty brutal miles. Marzocchi reliability is back from my experience, and hey, with a 3 year no-service needed warranty, I’d say they’re backing their products…