It's all subjective but I don't think you can go wrong with DoDo Juice Born to be Mild Shampoo, PH neutral so gentle but very effective. I try lots of different shampoos but always return to this. Also highly recommend DoDo Juice Supernatural Shampoo. It's highly concentrated so less is required, very slick suds which glide effortlessly across the paintwork, no dragging, great cleansing too. I alternate between those two shampoos most of the time.
Snow foam - never tried Auto Finnesse Avalanche but have tried a few others and can't recommend Valet Pro Neutral Advanced enough, Bilt Hamber Auto Foam comes ia close second.
Sealant - never tried Gtechniq C2V3 but might give it a go at some point. Am more of a wax person but often used in conjunction with Poorboys Ex-P. I like the finish of a wax on top of sealant, gives more depth to the colour and gloss imo.
DoDo Juice a Tropical Red Mist is a spray sealant and gives a lovely wet finish and is ace on DBP. It's not the easiest to buff off. Easy enough to apply though, but don't leave it for any time, buff off immediately, is the trick I think.