Take your own car seat. Even if there is one in the villa you need it to get from the aiport. If you have your own seat, there are many advantages
1) You are familiar with how to fit it properly and safely, if you get one from the rental desk you will have to fit it yourself (to absolve them of liability of incorrectly fitting it in the event of any mishap)
2) Your child is familiar with it and you know it is appropriate for their size and weight.
3) Most important imo, you are familiar with the history of the seat and know it has not been involved in an accident whih could have caused a weakness.

All of the above applies to one that is supplied by a villa owner as well.