Reluctantly says SWSH. Easier to multitask while playing and don't get me drunk while trying to get in some steps. Ignoring Marks, they're also the only games to indicate (albeit incorrectly in some cases) when a Shiny is of the rarer variety, which feels more rewarding since Gen. VI's Shiny boost. I did prefer SV's story and characters, but the minuscule overworld encounters really let it down for me.
I haven't played Let's Go or BDSP, but I feel I'd still lean more into SWSH since I can already Shiny-hunt all the Pokémon that occur in those games on my non-Switch games. The only real perk they'd have is being able to transfer to SWSH for "Glistening check" (the ones that could be transferred, anyway) without having to purchase a HOME premium plan.
New Snap was also good but nearly impossible to 100% on your own, even with the in-game hints. Also another that's difficult to play while multitasking/on the move.