The father of a young man stabbed to death in western Sydney says the Valentine's Day killing left a "huge gaping hole" in his family's life.

Wade Martinez, 23, and Jake Tortell, 21, on Monday faced a NSW Supreme Court sentence hearing after a jury found them guilty of the 2015 murder of George Garmo.

The 20-year-old was killed on February 14, two weeks before his birthday, and his "devastated" father said he had to organise his son's funeral instead of celebrating his 21st.

"For the rest of our lives we will continue to wonder what George would be like at each birthday and every milestone," Harith Garmo said in a victim impact statement that was read in court.

"There is now a huge gaping hole in our life, one that can't be filled and that has left our entire family broken."

Mr Garmo said he couldn't look to the past or future without heartache but he remained grateful to have raised his son.

"I remember the first time he was chased by a dog, the first time he told me he had a crush on a girl and when I first taught him how to drive a car," he said.

"It shatters me to know I will never be able to see my son find his soul mate, celebrate him getting married or watch him raise his own children."

He said he wanted his son's killers to receive the highest penalty so they couldn't hurt anyone else.

Martinez and Tortell were found guilty of murder earlier this year. Martinez was also found guilty of reckless wounding in company.

However, the court on Monday heard there was still some dispute over which of the men fatally stabbed Mr Garmo, who was found dead in the driveway of a home in Bossley Park.

The sentence hearing before acting Justice Jane Mathews was adjourned until August 11.

AAP