1M sats 

 I would say depends on your spending habits. Whirlpool has pools for 100,000 sats (~$27) good for small spends, 1,000,000 sats (~$270) good for larger spends, and the biggest pool of 0.5 BTC (~$13,000) good for mixing before moving to cold storage. 

 The only “spends” you should be doing with UTXOs is opening lightning channels. Even if you’re spending the whole thing, you get inbound liquidity. It’s very inefficient to do real on chain transfers that aren’t opening into lightning channels or VERY long term storage. 

 Think about it this way. You can always buy smaller UTXOs in the future and if/when the price appreciates you will be buying smaller UTXOs anyway.