  This paper is a summary report of the ICFA Beam Dynamics Workshop
'Accelerators for a Higgs Factory: Linear vs. Circular' (HF2012). It discusses
four types of accelerators as possible candidates for a Higgs factory: linear
e+e- colliders, circular e+e- colliders, muon collider and photon colliders.
The comparison includes: physics reach, performance (energy and luminosity),
upgrade potential, technology maturity and readiness, and technical challenges
requiring further R&D.
