Seriously... anybody tell me whether they prefer stain or water sealer? I don't care about the color, so I'm not sure stain is needed.
If sealer only, I have had better and longer lasting results with CWF brand (Clear Wood Finish) vs Thompson water sealer. CWF seems to last longer and definitely resist mold better than Thompson brand in my experience.
I also prefer a brush and medium nap roller vs an airless sprayer. I don't get in a hurry and hate cleaning overspray. But I will grab a sprayer on a big fence.
Don't buy cheap paintbrush or cheap roller naps.
CWF-UV is also available, has Ultra Violet protection if your deck catches a lot of sun.
decks on south side usually get sun all day
CWF is soap and water clean up for tools, brushes and such.
Thompson is paint thinner clean up.
Even with CWF, I still use a brush cleaner or mineral spirits on brushes after the soapy water clean up simply to be sure my $40 paint brush is clean and conditioned then neatly wrap with news paper, not tight but formed to natural brush shape.
I'm no pro and ymmv