Back in K-W and bored for Victoria day, so went out and biked around the universities area and all the way down King until the density stops past Downtown Kitchener, and can count 21 cranes. I doubt I'm missing any more within half a kilometer of King St., but there may be more cranes out in the suburbs or towards Cambridge. Probably a few more scattered around the region in suburban projects, so
@Pinski 's number of 27 seems pretty correct.
Student/universities area
250 Phillip St. (Elora House I believe) - 1
145 Columbia St. W (ICON145, towers C and D) - 2
199-205 Albert St. - 1
155 King St. N - 1
128 King St. N (One28) - 1
Rest of Waterloo
Barrel Yards V (road not built yet, tower name Royal Oak?) - 1
DTK
749 King St. W (The Bright) - 1
607 King St. W (Station Park) - 2
20 Breithaupt St. - 1
114/120 Victoria St. S - 2
55 Duke St. W (Young Condos) - 1
78 Frederick St. (Duke Tower Kitchener) - 1
51-53 David St. (Otis in the Park) - 1
120 Benton St. (Arrow Lofts II) - 1
242 Queen St. S (Ophelia) - 1
475 King St. E - 2
66 Weber St. E (Civic66) - 1
The problem with a comprehensive crane count of KW is that most building discussion happens over at WRConnected, so I doubt there will ever be thorough coverage of KW projects on this forum. Though we should have at least the major projects.