There is no "best neutral" paint colour. The colour that goes best with your own home including your flooring and furniture and any other tile work or appliances, etc. needs to be determined on-site. Are you painting the trim? Or are you keeping it what it is? And what is that? Or is it stained wood? If so, what colour? What's the floor like? So many questions, and no one magic colour that will work with everything...

For more help online here, pictures would help. But truly the best selection is going to be made in your home by you with a handful of different paint chips, or by a colour consultant who can visit you in person.

Cynthia has given you excellent advice in her excellent description of how the various elements in your home should affect your color selection.