The short answer
All nine coins SimVala takes get you the same eSIM. If you want the most privacy, use Monero. If you want a fast, low-cost payment, use Bitcoin Lightning. If you want a fixed dollar amount, use USDT or USDC. Beyond that, pay with whatever your wallet already holds.
If privacy matters most: Monero
Monero hides the amount and the parties on chain, so it leaves the least trace of any coin here. Paired with no ID to buy, it is the closest thing to a cash purchase of mobile data. It works exactly like the others at checkout.
If speed and low cost matter: Lightning
Bitcoin Lightning settles in seconds for a tiny fee, which suits small top-ups. You send from a Lightning-enabled wallet to the invoice shown, and your balance updates almost immediately.
If you want a stable amount: USDT or USDC
Stablecoins track the US dollar, so the amount you send is the amount you expect, with no market swing between quote and payment. Good if you do not want to think about price at all.
If you just want it done
Use the coin you already hold. Bitcoin, Ethereum, Solana, BNB, and Polygon all work. There is no fee math to do: the payment screen shows the exact amount, we add a small 0.2% for network costs, and the quote holds for 15 minutes.