Suggestion on Ghost enemies?

I am trying to create ghost as enemies for my game. I need suggestions for behavior And AI, not asking how to do it, just asking what should you think would work or any suggestion would be nice, on Ai and behavior and any thing else. Should I use “Top-Down movement behaviour” or not. Any opinion in your mind will be appreciated. Thanks

Should the ghosts follow the player directly, or try to avoid some obstacles also?

Pathfinding behavior might be useful for avoiding obstacles, but is more resource intensive (might create more lag, but it may still work fine).