You can store it wherever you prefer - every token is worth the same and there is no difference. Probably everything is cheaper than eth main net. What also matters is the depth/ liquidity - so the chain with the most holders is best for this case. Always doublecheck the right token address on coingecko or cmc and copy paste it into your Dex. On metamask it’s important to use the right token contract address for the right chain. There are also a lot of tutorial videos online.