I'm aiming for around 1500 per day.
This is my rationale for that number:
Theoretically, it should be only 500 less than what maintenance at my goal weight should be (of course that's just using calculators, but it should be a rough guess).
I have enough wiggle room that I can eat up to 500 calories more and still be at deficit.
It keeps me full (I eat very low carb, so my hunger is sated by the protein and fat I consume).
My energy levels are consistent.
When my weight loss stalls out, I'll add in about ten days at 2500 cals. Still a deficit, but enough to shake things up.
Your mileage will vary. Play around with what works for you!