Im no expert on shower caps, but for me the best ones are those that are big enough for your head and all your hair so nothing tries to slide out or pop off. I have a larger head, and I have found this one well-sized and sturdy (sorry for the terrible link):

https://www.amazon.com/Shower-Waterproof-Resistant-Washable-mikimini/dp/B0796M51YK?pd_rd_w=ONAGd&content-id=amzn1.sym.e3c57661-e58b-4056-99f2-4f3bd38ca08c&pf_rd_p=e3c57661-e58b-4056-99f2-4f3bd38ca08c&pf_rd_r=9WQV76BD6YYCJW5RQ4T5&pd_rd_wg=dcS4n&pd_rd_r=d9f571b6-dc39-499e-86fd-87472086b74c&pd_rd_i=B0796M51YK&psc=1&ref_=pd_basp_bia_rpt_ba_s_1_sc