Buy a tubeless kit if flats and pinch flats are ending rides and your wheel/tire combo supports it. Buy quality tubes + patches if you want simpler logistics or the rim is tube-only.
Either path still lives next to a home stand when you wrench. More in cycling.
Honest tradeoffs
Tubes — Simple, cheap spares, predictable. Pinch flats on rough MTB and thorns still suck.
Tubeless — Fewer pinch flats, lower pressure options, sealant plugs small holes. Messier setup, periodic sealant service, and occasional “why won’t this bead seat” evenings.
What to put in the cart
Related
If the bike is otherwise tired, fix chain and pads before obsessing over sealant brands. First upgrades after used-bike life: used bike upgrades.