Hi Edwin,
Put calendars work better if a stock starts in an uptrend… because these options will go out of the money and will be easier to close.
Also with call calendars… if a stock has a dividend coming up and you have short options that are in the money, you can see early assignment. Which isn’t fun, so I normally avoid using call calendars.
The greeks are basically the same but it comes down to assignment and executions.