Well,
Gyna, it is a deep question. I think Focus is better in some ways though I am not super thrilled with the scoring on some of the sections becuase the test is shorter.
However, if you are asking to pick which test to take, I am going to make your life very easy - GMAT Focus is the only available test you can take since Feb 1, 2024, so you will have to take GMAT Focus version (which GMAC has rebranded into just plain "GMAT" now that there is only one version.). So the current GMAT is what was known as GMAT Focus and the only available format. So no choice there.
PS. You do have a choice in how you take the test - you can take it online or at the test center.