"I think the Grand Slam was enormous. I think to win it at Twickenham, which is an unbelievably tough place to go with all the pressure that is around, made the Grand Slam the highlight of the year."
Best dismissed suggestions that Ireland's 16-9 win over New Zealand in Dublin two weeks ago had made it favourite to win the World Cup in Japan next year.
"I think favourites and underdogs is a tag that is thrown around in the media more than among the teams," he said.
"When you get to the top level, and when you look at the World Cup, you see teams like New Zealand which we were obviously thrilled to beat this month.
"They have been No. 1 in the world for nine years now and they are obviously a fantastic outfit. They are going to be tough to beat at the World Cup but I think below that there are a number of teams that will say that they have a real chance of going to the World Cup and winning it."I think for Ireland to be in that lucky position is phenomenal."
Frenchwoman Jessy Tremouliere won female player of the year, which Black Ferns great Fiao'o Faamausili was one of the nominees.
The only award the All Blacks won was try of the year which went to lock Brodie Retallick for his dummy and 30 metre effort against the Wallabies in Sydney.
Black Ferns Sevens star Michaela Blyde was among the early winners winning the women's sevens players award for a second straight year. Blyde scored 37 tries across the five World Series rounds, as well as dotting down nine times in the World Cup win in San Francisco and winning Commonwealth Games gold.
She was nominated alongside Portia Woodman and her captain Sarah Goss in the award for best female sevens player. She dedicated the award to Goss.
All Blacks prop Karl Tu'inukuafe was been pipped for Breakthrough player of the year by South African wing Aphiwe Dyantyi.
Former men's sevens skipper DJ Forbes received a Special Merit Award alongside ex-Wallabies captain Stephen Moore.
Winners:
World Rugby Men's Player of the Year – Winner - Johnny Sexton (Ireland).
World Rugby Women's Player of the Year – Winner - Jessy Tremouliere (France).
World Rugby Team of the Year – Winner - Ireland
World Rugby Coach of the Year – Winner - Joe Schmidt (Ireland)
World Rugby Referee Award – Winner - Angus Gardner
Try of the Year – Winner - Brodie Retallick (All Blacks)
World Rugby Breakthrough Player of the Year - Winner - Aphiwe Dyantyi (South Africa)
World Rugby Men's Sevens Player of the Year - Winner - Perry Baker (USA)
World Rugby Women's Sevens Player of the Year - Winner - Michaela Blyde (Black Ferns Sevens)
IRPA Special Merit Award – Winners: DJ Forbes (NZ), Stephen Moore (Australia)
Spirit of Rugby Award - Winner - Jamie Armstrong
Award for Character - Winner - Doddie Weir - Former Scotland international
Vernon Pugh Award for Distinguished Service – Winner - Yoshirō Mori - President of the Japan Rugby Union.
