If you are looking seo domain name. The it should have high number of backlinks (The backlinks should not be toxic), good number of traffic in the keywords. I find this 2 important factors.
For the backlinks, If you hand reg name you won't find it so you can go with expired domains as you can see the number of backlinks which indicates it has good DA (Domain authority) involved with their toxic level.
If you are looking for hand reg, Make sure you choose less competitive keyword. Or it is even better to choose long keywords to target specific niche, but I suggest to go with short as people will remember these name easily.
These are 2 options for you, Either you can go with expired name with good DA and high volume of traffic or else hand reg with low competitive and high number of search volume.
Well, I am not an SEO and Domain expert but I have 1 year experience in both.