Bos can be durable but the oils last once downpour, it's a show wax and imo not a wax i'd use without a decent base of shield or something like Z2. Shield is by far the pick of the SV bunch for me. Looks great and last well, reasonably priced (within the SV range).
Purple Haze and even the sort of sold school Dodo waxes are superb imo. Refreshingly honest and a friendly company. Rainforest rub has a special little feel to it these days, one of the originals.
Personally if I bought another Imperial Blue car or similar ilk, i'd buy a nice old style pot of PH and layer it. Not as my only wax but maybe for summer. Reminds me of waxing my first Frp, blew my mind.
Favourite wax, too hard for me? I love the old school and at times fussy nature of Glasur. It feels cool to use and Zymol are themselves pretty old school. Carbon like most have said is up there with the pick of the range due to price and performance, i'd certainly buy a full pot. I just wish after all these years they would sort out the lid issue, ruins a stunning pot.
Lusso Oro I think it's still one of the nicest waxes i've used (summer/show wax) Went on like oil and came off a dream, actually nicer to use than BOS.
Wax really can be a pleasure to use. If I could only have one for any car i'd pick Shield. Stunning all rounder.