A website in WordPress or the customized?
Depends on the kind of site you want to make. Performance-wise, both will perform well, and Google just recently backed Wordpress to bring performance improvements, so it'll be safe from degradation in SEO friendliness.
Wordpress is the safe choice since its ecosystem features a lot of premade addons, themes and experienced webmasters. Its omnipresence makes it unimpressive to use, as it already powers everything...
If you're looking to amaze with an unconventional experience, custom coding of simpler websites would be worth considering.
Wordpress Website is preferrable for SEO
WordPress is the best for SEO.
There is no such thing. Too many variables. It's a capable CMS. The more important question is what do you ultimately want to do. Then you pick your tool.