User blog comment:Yatanogarasu/Logia and Paramecia/@comment-3242083-20110212182810

I don't consider any of them weaker than a Logia, I don't even associate them this way. The mera mera example is the only one that really fits, however the atsu and kachi no mi are from fillers.

For the rest, I consider every devil fruit to be extremely unique and not "weaker" in any way. Some devil fruits might share a specific feature, like in the way the destructive power is delivered, or like the storage function...but else they to different to really compare.