Irony is in Steam, Construct 2 is way famous than Clickteam Fusion 2.5.
Look at how many reviews were counted.
Hard to say that's a valid comparison though, Construct 2 is the first commercial entry from Scirra, and most users got Steam keys alongside their license (Early Adopters did at least). Meanwhile, Fusion customers (being a long-time product) might mostly have had it or their previous engines before Fusion 2.5 was released on Steam (eg: MMF 2 was released in 2006, and the difference between MMF 2 and Fusion 2.5 isn't enough for a company doing well to upgrade and/or leave a review)
Although this doesn't mean anything as well: despite the larger number of reviews for C2, the actual review "rating" on average is slightly higher for Fusion 2.5 (C2 at 89% https://steamspy.com/app/227240 vs. Fusion 2.5 at 90% https://steamspy.com/app/248170), and that's the C2 any version (free and paid) versus just the paid Fusion 2.5 reviews.
Comparisons like that don't necessarily mean one is better than the other, I can't really think of an easy way to compare. C2 is new to the game so judging by popular games being created in one or the other is an unfair comparison too. In about 10 years if we still see Fusion games getting famous on popular YouTube Let's Plays (eg: Five Nights At Freddy's) and not so much the C2 games, then maybe we could worry about Fusion becoming a better tool, but I switched from the old Clickteam products because Scirra makes the way-better interface.