Economic theory journals for a refinement theorem about utility function representation
For theory you have in order of prestige... (I know subjective)

Journal of Economic Theory
Theoretical Economics
AEJ-Micro (only micro)
Mathematics of Operations Research (OR related)
Games and economic behaviour (only game theory)
Economic theory
Journal of Mathematical Economics
Social choice and welfare (only social choice)
Theory and Decision
Mathematical social sciences
$\ldots$

There are of course other journals that publish theory, like:

International journal of Game theory
Economic Inquiry
Economics Theory Bulletin

Feel free to add to the list.