So i am looking for a flashing protocol in stm32 , confused between j-link , st-link , swd and jtag , would you guide me which of the protocol is best for flashing the mcu . and suggest if anything better.

 

I use ST-LINK all the time. It takes two connections, SWCLK and SWDIO, plus VDD and GND.
I think SWD and ST-LINK are the same.