What's prefer, NVR or BlueIris or Something Else?

[Chaoscript]

I guess see what it costs to stay in Synology world versus buying stuff for BI.

I still didn't check the costs until the end, but before I go with something, I will do some research.

Are they annual/recurring license fees?

For Synology I think it's 1 time license.
And for BI it's one time payment, or if you want updates then you need to pay yearly payment.