Suggestions Best Sacred Seal in Elden Ring

Finger Seal below 27 faith.

Godslayer's Seal from 27 to ~70 faith. (While it does have a boosting effect, it has the highest scaling regardless)

Erdtree Seal from ~70 and above.

If you're going for a faith/intelligence or faith/arcane hybrid, the Golden Order and Dragon Communion Seals will do best if you're keeping the two stats roughly equal.
 
When it comes to staves, it really depends on your Intelligence (Int) level. Different staves scale differently, with some showing significant gains early on and others getting their boosts later. The best staff for you will largely depend on your Int. If your Int is 41 or lower, the Demi-Human Queen's Staff is your best bet. With an Int of 80, you should consider either the Carian Regal Scepter, which is my personal preference, or Lusat's Staff. While Lusat's Staff technically deals about 11% more damage, it comes at the cost of a 50% increase in FP usage, which I don't think is worth it.

Now, let’s talk about other stats. If you're also raising your Faith (Fth) and plan to bring both Fth and Int up to 80, the Prince of Death's Staff will give you the highest Spell Scaling. If you're focusing on Arcane, the Staff of the Albanuric can utilize your Arcane for Spell Scaling, though you'll still need Int to cast the spells.

The spells you plan on using also matter. If you're going for Carian Slicer and similar spells, wielding the Carian Glintstone Staff in your offhand will boost their damage. On the other hand, if you’re focusing on Night Sorceries, the Staff of Loss is the way to go.

There are a lot of factors to consider when choosing the best staff. For general use, I'd recommend sticking with the Carian Glintstone Staff if you're maxing out your Int.
 
Finger seal is great but I personally prefer godslayer seal or Erdtree Seal.

Godslayer seal for blackflame magic, and Erdtree for the rest fo Golden order related incantations. Dragon communion seal is also good for dragon based spells