Dragons that follow the Tenets of the Balance are almost always partially neutral with roughly 75% of all Harqualian dragons being True Neutral. (The Majestics are always TN.) Around 20% of the other dragons on the continent are LN, NE, NG, or CN. The last 5% (or less) are consider to be "Rogue Dragons" who have turned their backs on the Tenets and are LG, LE, CG, or CE. These rogue dragons are considered dangerous extremists by the Majestic Dragons and some of the followers of the North Gods.
Note: Majestic Dragons cast spells as druids instead of their typical spellcasting. They may also wild shape like druids into any natural form equal to their size or smaller (equivalent to the creature chosen plus the Half-Dragon template). This doesn't include other types of dragons, of course.
It is generally believed that there is only one Majestic Dragon per type of dragon but that isn't true. Yes, there is usually one Majestic that stands above its peers but that restriction is more regional than absolute. For example, as noted previous about the very old blue dragon (Thunderback), who lives near the city of Helt, is considered a Majestic Blue Dragon. However, he is the specific Majestic Blue of the Thunder Lands, of which the Strandlands is a part. (There isn't a more powerful/respected "neutral" blue dragon that lives anywhere in the Thunder Lands, although there are other "neutral" blues who consider Thunderback to be their liege.) There are other Majestic Blue Dragons in other parts of the continent and Caerth knows that Aeron once named the most powerful Majestic Blue as a female great wyrm who he called The Azure Goddess. She lives in the huge desert south of The Thunder Lands known as the Great Expanse.
Aeron told Caerth that the most powerful forest-dwelling Majestic Dragon in the Thunder Lands is an ancient green dragon who Aeron referred to as the Son of the Hunt. This dragon (who is called Mab yr Helfa in Sylvan) lives in the Verdalf Forest and is an ally of the hunter elves of that large forest. While the Verdalf Forest is far from the the Strandlands, Caerth knows the forest is south of the Great Forest but close enough to have had to worry about the rising power of the Blood Elf Lands. Caerth doesn't know enough about the forest's denizens to know if they've come into direct conflict with Vok and his blood elves, but it is likely. Aeron might know more.
Closer to home, Aeron told Caerth that there is an old female bronze dragon who lives deep in the Halfling Woods who is called Summerwind. While she isn't a Majestic, she is a devoted follower of the Tenets. However, she leans more towards good than evil, so she often sides with goodly folk including the halflings who share her forest home. Aeron told Caerth a tale that she is the guardian of a sacred druidic grove. (You can come up with the story.)
When it comes to druidic circles, Caerth knows that there are several in the Strandlands (but not all by name). However, if there is an archdruid living somewhere in his homeland, Aeron never mentioned such a powerful druid. Besides the druids who live in Halfling Woods, there is a notable druidic circle far to the northwest in a mid-sized forest (for the Strandlands) known as Toldareon Forest over 260 miles west-northwest of Belporte along the Strandshore. The Toldareon Circle is led by a druid known only as Casendor. Aeron never mentioned anything else about the man other than he is respected by the denizens of that forest and most of the farmers and ranchers who live around the forest's fringes.
There is also a druidic circle in the Bluewood Forest but even Aeron didn't know much about its members. The Blue Circle is very protective of the Bluewood Forest and the other nearby forests including both the Aridledge Woods and Nolanar Woods. (See your Lay of the Land map.) The denizens of the Bluewood Forest are known for being a bit more isolationist than those living in the Halfling Woods and other more northerly woodlands.
Aeron never mentioned a druidic circle based in the Wasting Shores, but it wouldn't be surprising if such a circle existed with Thunderback as their mentor (or leader?).