Q. If one has a choice to attend shul either both days of Rosh Hashana or on Yom Kippur (can’t do both, such as they are not letting people in to avoid overcrowding during corona), which is better? 

A. Horav Shlomo Miller’s Shlit’a opinion is that he should choose Rosh Hashana, since besides that it involves two days instead of one, it is also first and we rule that a mitzvah that came to you, should not be postponed. (Remah O.H. 625:1, etc.)

Rabbi A. Bartfeld as advised by Horav Shlomo and Horav Aharon Miller Shlit’a