Fixed or removable vagina?

Fixed/built-in vagina: 
A fixed vagina is built into the dolls body.

Pros:
1. More realistic feeling.
2. Better aesthetics.

Cons:
1. It is harder to clean and dry after use. The doll is quite heavy, so I guess you don’t want to take her to the shower after each time. 😉
2. If something is damaged there, you can’t replace the vagina. Instead you’d need to replace the doll.

Removable/insert:
A removable vagina is an insert that can be removed for cleaning and washing (like a flesh light).

Pros:
1. Very easy to clean and dry. You can turn it inside out, clean and dry it, turn it back, done.
2. You can replace it, if it’s damaged.

Cons:
1. A little bit less real sensations during intercourse, as it can slightly move around.
2. There is still a risk of damaging your doll, when you put the insert in and take it out.
3. If you spread her legs, you will see the insert in her vagina.

Conclusion:

There is no big difference. You just have to choose between ease of use/cleaning vs. aesthetics and a more realistic feeling. It’s up to you!