Some tools fall into the category of "bigger really is better" and planers are one.

I have an 18" and there are times when I wish it was wider.

But then eventually I'll have a wide belt sander and that will help satisfy those times to a degree.

The other thing to specify is whether you have interest in investing time and effort into a used machine. They can be a bargain financially if you are willing to do some refurb.

Segmented rollers are really nice when you go wider as well. Feeding multiple pieces at once let's you use more of the bed and is obviously more efficient