Since 2013 or so, I believe the issued laptops have been predominantly MacBooks. That being said, it's important to note that CGA will issue you one regardless of whether you own one or not. Per the 2024 Parent Handbook:
"
Please note that every cadet will receive a laptop computer before the academic year starts, even if they already own one. You might consider purchasing your cadet a printer or desktop monitor (may not exceed 23”) if they request one; these items and other electronics are available from the Cadet Store."
So, my advice to you would be to purchase one that does the job and gives you what you need to be successful at Marion, but don't break the bank on a top of the line computer. Get a serviceable one at a reasonable price that you can perhaps give or sell to someone later on if you are accepted to USCGA for the Class of 2025.
Here's another thread on the topic:
https://www.serviceacademyforums.com/index.php?threads/computers.55678/