There are a lot of “best of 2013” lists out there. Here’s some that mention Conundrum books:
Paul Joins the Scouts by Michel Rabagliati made it onto Brigid Alverson’s top 10 comics (listed in The Comic Resources’ Robot 6).
The Sweetsburg Archives by jonathanreidsevigny made Emily Raine’s “best books of 2013” in CULT MTL.
Other Stories and the Horse You Rode In On by dakotamcfadzean made Rob Clough’s top 25 long-form comics list.