Perhaps you can't decide which CPU to buy, you can make a choice after reading the comprehensive test Intel Core i3-8121U Cinebench r15 score multi and single core and decide is it a good processor or a bad one to buy, how powerful is this processor. Here is useful information from Cinebench r15 benchmark. A careful review of all the technical characteristics, to make it easier to read, is summarized in the table. After looking at the data this test and video, you can already make an informed decision about do you need to buy Intel Core i3-8121U or not.
All the figures in the article above do not mean that taking them into account you should undividedly trust a simple comparison of these figures. Better to watch benchmarks video and read the opinion of real owners of Intel Core i3-8121U before deciding buy this processor or not.