This isn’t a new question by any stretch. That being said, there are two sides of the coin. I am a Cohen muchzak, and will have Yohr Tzeit on a Shabbos. I asked Mori V’Rabi Rav Schachter, and this was his response.
Is it better to get Maftir on that day, or should I get the Aliya of Cohen, there also being a Minhag to “accumulate Maftirs during the year, something I have never sought to impose or ask for wherever I daven)”
Joe Alpert (niftar 2 years ago) told my father that the first year he had yartzeit he went to Rav Moshe on Friday morning on his way to work and asked which aliyah he should take in honor of his father’s yartzeit. rav Moshe said it is better to take one of the ז’ קרואים and not maftir. Later that afternoon when he came home from work he had a message that rav Moshe had called back and said that he made a mistake and more proper is to take maftir as there are more brachos, and it will be a bigger zchus when more brachos are recited.