An important factor is the flow rate. The Watts 263A does 4 - 4.5 gpm which is pretty decent. If you have a filter, it can really drop the flow rate a lot and the best regulator with high flow won't help you. If you want a filter, there are ones with good flow rate available.
The basic inline Camco and Valterra ones have low flow rates. The next step up would be a Watts 560 series good for 2 - 2.5 gpm. Watts makes bigger and better regulators but they start to get heavy and probably won't help a lot. Lead free versions are available too.
RVwaterfilterstore.com is a good place to buy a regulator and possibly the best pricing you'll find anywhere. If you don't see exactly what you want, just ask them. I got a 263A from them without hose adapters.
This is what I am about to install in ours. Watts 263A, whole house 10" filter, Pentek FloPlus filter, tell-tale gauge on incoming side, new all-brass water inlet, arrestor and Shurflo strainer on the outside. Also bought a Valterra high pressure 5/8" hose. I'm using "swivel adapters" at the regulator and gauge assembly ends so I can easily remove it in the winter in case water is trapped inside. Total cost about $150. I paid $20 for the filter housing (no filter) at a wholesale supply place and the identical thing at a local RV dealer was $200!!