Amazon publishes details of both exams on their web site. The new exam looks like a better choice than the previous exam. Given the statement:
"We have recently updated this exam to cover new services and architectural best practices."
I would take the new exam as this better fits with current AWS services and features.
Note: People who take the exam are not allowed to provide details of the exam. I have not taken the new exam. I have the SA Pro, so I am automatically recertified for the associate.
However, given the new longer time to complete the exam and fewer questions, I expect that the questions are harder and better thought out than the previous exam (which sometime made me ask "Who wrote that question?").
AWS Certified Solutions Architect - Associate
Certified Solutions Architect Associate Exam Guide