Look into 4NEC2. It is free. I believe to a large extent, the differences in
the programs are the way you input antenna parameters and the way the results
are displayed but the output is the same because they use the same calculating
engine.
4NEC2 come with a bunch of antennas already modeled that you can play with to
get familiar with the program. I have made many models of antennas myself,
and getting quite a collection of antennas that are of interest to me. I
don't know about the other programs but I can tell you that I have spent
dozens of hours learning and experimenting with my 4NEC2 and still have a lot
to learn but when I finally learned about "cards" (from reading the generic
documentation) then things began to make a lot of sense.
It even has 3D displays but I haven't gotten that far yet !!

Rick K2XT