During a low-fee environment, spend the smaller UTXOs for privacy preservation (recall that people can see the size of your UTXO when you spend on-chain, so the smaller the better from a privacy standpoint).
During a high-fee environment, spend a single, larger UTXO to minimize fees (fewer UTXOs = lower vBytes = lower txn fees).
In all cases, only spend UTXOs that have already been mixed via collaborative transactions (aka coinjoins) for forward looking privacy preservation.
Also in cases, minimize UTXO “dust” by consolidating UTXOs from time-to-time so none of your UTXOs are less than 300K sats, or even better, 1M sats.
Granted, these are rules of thumb only.