We stayed Feb 27 thru March 7th, this year. The year before we stayed mid-Feb.
Most recent stay, did not see many tour groups at all, must have been too late in Feb? However, there was a huge amount of marathoner's and families who stayed over the week following the marathon at WDW. It did seem crowded then but not unreasonable. We expected it to be slower but were unaware of the post marathon crowds. I guess it makes sense that the runners would want to rest and enjoy the parks after the event.
The Mid-Feb visit in 2017 was not very crowded to us. It seems everyone has a different perspective on that - the degree upon which they think it is crowded or not. We saw 2 tour groups which were well behaved with older tour managers. We saw large groups of cheerleaders which were no problem either, as we just stayed away from them.
But others have apparently seen a lot of tour groups, so I guess you have to make up your own minds.
We did check the holidays (Presidents day for one), cheer events, etc and try to avoid busy times. It worked somewhat, but all was okay in the end. We enjoyed our visit.