What method is best for deck reconditioning & which product(s) are considered superior and/or best to use?

If you use a quality oil base sealer/stain after the cleaning and prep forget about a "water seal". I lived in the inland North West where it not only rained and snowed but the temps. dipped below minus thirty, and south east Alaska where precip exceeded seventy inches a year, plus freezing temps. If you want a natural wood finish, all of the manufacturers produce a clear oil base sealer that will give you maximum protection. The same protection can be obtained using a tinted (stain) sealer. Don't listen too closely to the Lowes and Home Depot salespeople who want to SELL.