Privacy and utxo efficiency in regards to fees are often at odds. For privacy I think it would be best to have various sized utxos (to a degree, obviously not too too small) since you often have various sized payments. You don't want to have lots of 100-200k sat utxos and then make a payment for 5 million sats, resulting in having to combined a bunch of utxos which is often bad for privacy.  But as you insinuated it isn't good to have utxos that are too large, since that means if you make a small payment with a large utxo then the recipient is aware of a significant portion of your wealth which is not good for privacy either. As well the recipeint can track your future transactions since you will most likely be using the change output you received for future payments since it is a large portion of your wealth.

Overall I think various sized utxos are good for privacy.  Most utxos you don't plan on spending soon should be 1 million sats an above due to fee efficiency.