Blue Dasher is an extremely common species, perhaps the most abundant dragonfly in eastern North America, but I miss most of their flight season while I'm in Algonquin Park, so am always happy to see them.
Familiar Bluets can be ridiculously abundant at man-made ponds in September.
American Rubyspot is perhaps my favourite ode I've seen. The gold and green females and metallic red males are both spectacular.
Although this species is abundant at this location (I had about 10 individuals today along 5 metres of riverbank), I have never seen one more than two or three metres from the water.
Other typically southern species I was happy to see included Black Saddlebags and Eastern Amberwing. I was also glad to see familiar faces like Eastern Gray Squirrel and Northern Cardinal after several months.