In the case of use ICs, electrical parameters is better, but the reliability is low due to the IC and the transistor operates in the heavy-duty and damaged by voltage spikes and the a small driver board heat from LED . The price is higher because in addition to IC and transistor use ultrafast diode, special inductor with gap for LED and suppression inductor after the rectifier.
We shows a decent schematic, a bit more complex, but reliable. In comparison to the cost of 12 LEDs the cost of additional parts in production is not significantly greater, while providing greater reliability. High reliability because with increasing voltage the transistor is closed and voltage spikes even up to 600 volts are not harmed. The current of the LEDs is stabilized and the main voltage fluctuation do not change the current in LEDs. In the event of termination or closure of even 10 LEDs, the current of LEDs will remain unchanged, leading only to a decrease in brightness. Since the circuit is not isolated from the mains, it is necessary to connect them through residual current circuit breaker. Brightness 1440 lumen.