safest and cheapest network to store my USDT in ?

Hello. i'd like to know what's the cheapest yet most safe network to store my crypto on. i have +100k in USDT as of right now and i use a cold wallet to store it (Tangem).

which one is better and cheaper and what makes a network better than the others?

also, should i store my profits in USDT or USDC or DAI ?

my wallet currently supports the following networks: ERC20, TRC20, MATIC, ARBITRUM, BEP20, SOLANA, FANTOM OPERA and OPTIMISTIC.

im not a crypto trader. i trade forex and withdraw my profits via crypto. any help ?