The counterparty risk for Wallet of Satoshi and Cashu users is that the server operator might run away with the funds. Liquid users face the risk that multiple federation members might collude to steal the funds. Spark users face the risk that the service providers might collude with the previous sender to double-spend the received funds. The counterparty risk for Ark is that if the user stays offline for too long and their VTXO expires, the service provider may be able to take control of it.

You could imagine a wallet that works like this: for balances under 1,000 sats, it uses Cashu; for amounts over 10,000 sats, it switches to Spark; for over 100,000 sats, it uses Ark; and once the balance exceeds 500,000 sats, it sets up a self-managed Lightning channel.