Go with what material you gravitate to. What's your style..
The considerations you noted involving durability and water resistance are of little concern. When you get more experience with a razor, you will find it will not be covered in soap, or need serious cleaning.. No need to throw it in an autoclave..
Regarding wood.. Not all wood is equal.
I had African Blackwood in a wet moldy basement for a long time, not one bit of mold or rot. So hard oily woods are infact quite durable and mold resistant.
This is not a combat knife headed to a tropical war zone.

It seems as though even with this information that you will probably still lean toward synthetics, this is perfectly fine.
What's more important is what really makes you happy.
Welcome to the forum! I hope you thoroughly enjoy yourself and find what you are looking for.