TotK is better in every way but BotW is once in a lifetime experience due to how contemplative it can be. You’re not going to play both at the same time and they benefit from playing in order. If you’re low on cash buy some used copy of BotW off someone on Vinted* and sell on Vinted once done, then do TotK.
* or Craiglist or OLX or whatever is used locally where you live
Apologies for my scatterbrain. In that case I’d go with BotW because it’s shorter/focused (others will say it’s too minimalist) and you’ll get to experience a modern Zelda game. Also, if you don’t own Switch 2 it runs good enough while TotK was just a bit too much for Switch 1.