Suggestion for simulation of broadband ESAs with metamat

Hi,

I'm researching which types of EM simulation tools are commercially available to aid my project. HFSS, CST MSW, and COMSOL are the 3 that have caught my interest (since we have copies of COMSOL in our lab). So here is the broad outline for the antenna that I will be researching:
-Electrically small
-Broadband (up to 100 GHz, 1 THz, Infrared, etc.)
-Metamaterial structure
I am interested in creating a 3D model with accurate metamaterial properties to simulate the radiation pattern, antenna efficiencies, and other parameters. Here are some of the thoughts I've gathered on the packages that I'm considering, assuming they all handle metamaterials appropriately:

HFSS: EM FEM-based code that generally uses more PC memory and takes longer to converge to a solution. However it can handle complicated geometries (doubt that impacts me). Better for narrow-band simulations.

CST: EM FDTD code that requires more PC CPU power and less memory. It generally takes less time to run than HFSS for a given antenna model. Better for broad-band simulations.

COMSOL: Multipurpose FEM-based program that is much less user-friendly than CST or HFSS but could be just as powerful, which is up to the user's capabilities.

I'm leaning towards suggesting CST as a viable simulation tool, but I'd like to gather advice from those who have had experience with either or all 3 programs and what the pros/cons are for each.

Thanks in advance!