Do you want the strongest and most beautiful splint woven seat? Then use Hickory or Oak splints. Hickory splints are used in rustic chairs, porch rockers and other early American chairs. Hickory spilnts will out last any other splint that is available. Oak Splints are the second most duralable splint.
I do not carry the splints directly but below are links to 2 very fine family run businesses.
Hickory Splints Newberry & Sons.
Oak Splints Owens Oak Baskets.