I'm much more of a purist regarding what was and wasn't "British Invasion". The Brits "invaded" from around 1963 to 1965. Once the Brits knocked down the barriers, and the US bands caught up with them, the "invasion" was over, and British bands simply worked both sides of the Atlantic, as did the American bands. Also, the British Invasion included both rock music and pop music. I realize this is the "Classic Rock" forum, but I make no excuses for the fact that I enjoy both rock and pop music. Both have their place.
My favorite rock bands from the British Invasion:
Beatles
Stones
The Who
The Animals
My favorite pop bands and acts from the British Invasion, or at least the ones I can think of off the top of my head.
Herman's Hermits
Dave Clark Five
Peter and Gordon
Chad and Jeremy
Petula Clark
Gerry and the Pacemakers
Tom Jones
My favorite British acts who came over shortly AFTER the invasion, or at least the ones I can think of off the top of my head.
Moody Blues
Cream
The Yardbirds
The Crazy World of Arthur Brown
Fleetwood Mac