There is no best Dragon Lair, ideally you'll visit many of them. The Eggs hatch starting at server save, and after a few hours have passed most of them have hatched already. If no one visits the place, you'll find 20, 30 and as much as 50 Dragon Hatchlings at once. The thing is, they won't respawn, so once most of them have hatched and the spawn cleared, that place won't be good again until the next server save.
With that in mind, what you should do is visit a few dragon lairs. The later you go, the more eggs will have hatched, but also the higher the chance of someone else having visited the place and killed all the dragons. There's no method here, it will depend on your available time, server population and just luck.
These were the places I visited and found several Dragon Hatchlings a few hours after server save:
- Zao mountain, going up one floor from both sides.
- Darashia Dragon Lair
- Edron Dragon Lair
- Ankrahmun Dragon Lairs
- Thais mini Dragon Lair around lava
- Thais Dragon Lair (Naginata Quest)
Other dragon lairs also have nests, such as Venore, so you should probably visit them too if you have the time. If you get lucky with the timing and full spawn you can easily kill hundreds of them in a single day: