Maple has a density rating of 1450, regular red oak is 1290 (QS white oak is 1360) and walnut is 1010, so maple would be a better choice.

I love walnut but it is more delicate , I think pedestals or inset legs are preferable and I would do a plexi top for the table for everyday to protect the wood and just remove for larger gatherings and use table linens .

My table has 4 legs and an extension on each end. The legs are quite obstructive when trying to squeeze in the extra seats.

Their is a difference in soft maple and hard maple. That said, equally as important will be the type of finish thats applied and how its applied.