The coronavirus so mixed up scheduling for anime in 2020 that I decided to just wait and start over in 2021. So here are my top choices for the current Winter season. All three anime themselves top my list for this season as well.
Shake! Shake! Shake!
Dr. Ramune – Mysterious Disease Specialist 
Performed by Uchida Yuuma
I like jazz and jazzy openings. One of the first things that caught my attention in the anime Oh! Edo Rocket was the big-band sound used by Honma Yusuke in the score for that show. This OP is more modern than the Goodman-like sound Honma used, but the brass parts are terrific.
Full version is here.
Wonder if King Records funded the anime to promote this song?
Iru Kosui (“Color Perfume”)
Horimiya 
Performed by Yoh Kamiyama
Horimiya may be the best high-school romantic comedy I’ve seen despite going off the tracks a bit in episode seven. Given that high-school rom-coms are the bread-and-butter of anime these days, that’s a high bar.
Both its OP and ED make my list.
Yakusoku (“Promise”)
Horimiya
Performed by Friends
Removed from YouTube. Again, you can watch it in context here:
https://www.funimation.com/shows/horimiya/a-tiny-happenstance/
Kemono Michi (“Animal Path”)
Kemono Jihen
Performed by Ono Daisuke
Kemono Jihen has more visibility than Ramune, but it’s hardly on everyone’s lips. Too bad since it could be the top show of the season. Ono appears in the series as a mischievous Romanian vampire.