SEOSEO or paid advertising
The fastest way to attract visitors to your site is using paid advertising such as "pay per click." A typical example of such ads are paid ads on Google, known under the brand Google AdWords. Depending on the amount you pay, your site will appear above, beside or below the other search results.
Google AdWords definitely lead to increased visits to the site, but it only lasts until you pay for this service. Otherwise your traffic disappears and this automatically reflects sales.
You should also not forget that a large percentage of users ignore sponsored links.
SEO is a completely different way to attract visitors to your site. Above all, it is seen as much more natural, since your site appears on regular results of the search engines.
Although you have to wait some time to see the results of SEO, their effect, as opposed to paid advertising, is incomparably more durable.
If you are looking for investment with the highest return, which would increase your ranking on search engines and reduce your long-term costs for advertising, then SEO is the best solution.
Paid advertisements in combination with SEO
When you want both long-term and fast results, then the best solution for you is a combination of paid advertising, Google AdWords and SEO. After reaching the results of optimization, paid advertising can be reduced or become redundant.