Bit late, but here's three.
Favourite spring plant: primulas.
Favourite summer plant: phlox.
Favourite fall plant: New England asters.
They're all very pretty, very hardy here, provide lots of colour, bloom a long time and are easy to maintain.
My most favourite of all: garden phlox.
(Shortwood, Bright Eyes, Düsterlohe (Nicky) and a red I got from another garden: July 30, 12)