Maine First: I've been to a dozen different shops since legalization in ME. Two best I've found are Landrace and Seaweed, both in the Portland area. Both are vertically integrated cannabis enterprises that grow, process and package their own stuff. Outstanding quality.
Atlantic Canada: I'm up at my place in Newfoundland. Since I'm here for 5-6 months, I did a big buy of flower and concentrates with stops in government shops in NB and NS. The NB shops are amazing, with two hundred or so in-stock items in each of the bigger shops. This is my third or fourth year stopping in NB and NS on my why here. Two best flowers: Misku Bucket List and SensiWizard. I've now tried around 15 different concentrates up here and found one that stands out: Reef Organic High Seas Ghost Train Rosin. Amazingly good product and Reef Organic is the first fully Green cannabis grower in Canada.
https://www.reeforganic.com/organic-cannabis/