United will mark the Scot's trophy-laden 26 years in charge at Old Trafford by unveiling a statue of the 70-year-old outside the stand that already bears his name on Friday.
Wenger has had many close duels with Ferguson during his own 16-year Gunners tenure but says his rival deserves "huge respect", while David Beckham and Gary Neville paid tribute to their former boss.
Wenger said: "I don't remember anybody else being at the top, top level for such a long time.
"In some ways it is scary as well because you think when this guy leaves the club, no matter of the quality of who comes in after him, it will be a huge hole.
"The club will be destabilised even if the guy who comes after him is top quality because the print of everything, the life of everything, revolves around Ferguson so much at United.
"He has to be immortal so the club doesn't suffer! His commitment is always there, you never feel that his commitment is weakened.
"What I admire most is his forward-thinking. He is always ready to move with the times and never speaks about what he has done. He knows when to renew the team, when to make changes, and that is exceptional because you can sometimes be lazy when you have so much success.
"He's never been like that, he's always on his toes and he can renew what is needed, when it is needed. It is a job where you need to dedicate your life to football and Ferguson has done that and that deserves massive respect.
"He has won absolutely everything and, of course, that is something exceptional."
Ferguson won the first of his 12 Premier League titles with United in 1993 and
has also achieved Champions League success twice, along with five FA Cup triumphs.
Beckham, under Ferguson and was a member of six title-winning sides before leaving for Real Madrid in 2003, has had his fall-outs with his old boss but added: "He's been so successful because he's passionate about Manchester United and he's a born winner.
"He knows how to win games, how to handle pressure and how to look after his team and his players. He was like a father figure to me.
"I was scared to go and knock on his door because of who he is but he always made me feel as if I was part of a family and that's how you feel when you're at Manchester United."
Ex-United defender Gary Neville said: To be at this club for so long is staggering. You would never believe it could happen.
"I've said before, United had Sir Matt Busby, now they've got somebody who's replicated his longevity at the club and surpassed his success - you would just never believe it could be achieved."