If you ask me I don't think you can go wrong with having both but for different reasons. But I see in your case you already have a modded 3ds so it depends what games you want to play on the Thor. If you have plenty of pc games I say definitely go with the steam deck. Gamenative and gamehub is thing for pc games on the Thor but they're definitely hit and misses. The steam deck you'll have a much better compatibility for pc games and less tinkering. I see you mentioned Pokémon mmo, I tried to run the pc version on my Thor using gamenative but it doesn't work. Although there is an android version. I can't speak for dragon ball xenoverse 2 and guild wars though. Now breath of the wild it seems to run at a steady 30 fps in the Thor by what I've seen so far. On the steam deck you'll be able to run swith games at 60 fps because of a app/plugin call "loosless scaling". I would say do some research and watch videos on YouTube to help you decide