There are many sealing technique's out there.
The ones that so far are capable of sealing a being. So far we have the shiki fujin. The Shisho Fuin and its more advanced form, the Hakke no Fuin Shiki. Personally i like the Shisho Fuin or its variation, because they can achieve the same results however without the expense of the user's life. It seems however because of its implication's though going by the db entry it can be used for battle its very impractical, therefore limiting it to a technique used to make a jinchrucki. Similar to bee's Tekko Fuin which its cannon to be inferior to the Hakke no Fuin Shiki
Other sealing techniques which rivals the shiki fujin is chiyo's Shishi Heiko and bee's Okutopasu Horudo, though these two are limited to human being's and not bijuu's like the uzumaki technique's above.
When it comes to sealing technique's though the shiki fujin is the strongest it does have its downside's. Some might argue that its downsides outweigh the upsides, others would disagree. Personally i dont think there is a best sealing technique because all have weaknesses, however if i was to choose one, id take chiyo's Shishi Heiko.
Lmao i forgot sealing tags, however those are the basic sealing ability
Legendary sealing weapons however makes it at the Top of the list, however this is fuinjutsu so ill leave it there