Which T Money Card to buy ?

Hello everyone,

We are arriving in Seoul incheon Airport next week.
We can see on internet that the T-Money card is very important, but somehow it needs cash to top up the card.

Somehow I can see on Instagram or over social network that there is new stuff such as the WowPass or Check In Seoul. It's all so confusing.

There is also combo with LGUplus esim https://www.lguplus.com/korea-sim/eng/pc/support/blog/korea_travel_checkinseoul_esim

What should we doooo 🤣