Which method is the most effective for SEO in 2022

For gambling / Sports betting sites - PBN unique , Niche PBN , RGP - will boost rankings .
or
Check with this - https://www.fortismedia.com/en/articles/10-seo-tips-for-online-casinos-and-betting-sites/ - It shows you 10 SEO Tips for Online Casinos and Betting Sites with more detailed .

Hope this Helps !

On page SEO

The method really depends on the type of niche, and for your niche which is pretty competitive nowadays but also has a lot of potentials, I would definitely recommend writing guest posts and publishing them on different directories that list various casino programs, you'll just need to do a research first and find the best ones. Also, you can ask them if they are interested in some other type of cooperation, as you could share links and gain more traffic that way, use some banners, and so on. Another recommendation would be to stay active on forums and online discussions in general related to the casino and gambling industry as this will also boost your online visibility.

People here love to parrot each other and send OP on overpaid, underperforming guest posts search, 80% of ALL guest posts are garbage links on garbage sites...

If you do your own research and outreach (which can take weeks) you can find a view gems but these gems are extremely expensive, $100+ per link is normal...

For that amount of garbage links you are better off building your own PBN OP, also noticed that of all these parrots that are recommending guest posts, most of them are link sellers flashing their sigs. #justsaying!