Udyr Runes JG Question (Help Please!!!)

Ok, so I main Udyr, but I know nothing about runes, I know how masteries work but not runes.

My rune page for Udyr now is 2 Movement Speed & 1 CDR Quints 9 CDR Glyphs 9 Marks of Attack Speed

But its the seal I don't know what to do on. Flat health, Scaling health or % health? If you know can you explain which one and why? Thank you :D

BTW I don't go sated, I go runic echos for that w spam and flame god. If that is important

Mastery Keystone is obviously strength of ages.