We have granite countertops in kitchen and baths. Love it.
We have marble floors in kitchen, entry, mud room/laundry room, family room, and one of the downstairs bathrooms. Big mistake, in my opinion. It was here when we bought the house and would have been a huge undertaking and very expensive to remove and replace.
While the marble is truly beautiful, it is high-maintenance, very expensive to have cleaned, polished, and sealed. If you spill red wine or similarly pigmented things and don't get it up immediately, there is a chance of staining. Even if you get the pigment out, there is often a spot residue that's left behind.
In short, it's a pain.
Stay away from marble for kitchen countertops and go with granite or quartz. They're both beautiful and durable. Quartz needs no maintenance. Granite just requires sealing once a year. Easy.
When we renovated two years ago, I researched both quartz and granite.
I liked granite because there are more color and pattern choices, although quartz has come a long way in that regard, and there are many beautiful options.
Since you're only putting the countertops in order to sell, go for a more neutral color and subtle pattern that will appeal to a wide variety of buyers. It would be a shame to spend thousands of dollars on a pattern only to have potential buyers feel it was too personalized.
Hope that helps and good luck with the sale.