Which one?

Finally decided to up the ante in terms of resistance to build muscle & lose fat..

I'm down to 2 deliberations -

Ankle weights - https://www.amazon.in/dp/B07CCMN9JZ/ref=cm_sw_r_cp_apa_i_-XS9EbP2R83Q2

Resistance bands - https://www.decathlon.in/cross-training-accessories/resistance-bands-13103?query=Band

Which one do you suggest as a first purchase? I'm presently using 3-4 kg dumbbells.