Which ON/OFF controlled Offline Flyback is best?

[ocset]

Hello,

The attached are two Offline (230VAC) , isolated, 15V,2W Flybacks.
They both use ON/OFF control with the UCC28C44 controller.
The feedback isolation is done by the digital isolator SI8710.
Which Flyback would give the best  Vout regulation?
Do you agree that the one with the BJT current source regulation would give tighter Vout regulation?

SI8710 digital isolator
https://media.digikey.com/pdf/Data%20Sheets/Silicon%20Laboratories%20PDFs/Si87xx.pdf

UCC28C44
http://www.ti.com/lit/ds/symlink/ucc28c44.pdf
 

[station240]

One mistake in both circuits, you need to power VDD (pin on the SI8710 from the aux winding not the secondary. As it is you have a diode junction between primary and secondary halves, this defeating isolation.