If you want one to bring the room to life, the answer is "I Want It That Way" by the Backstreet Boys. It kills 100% of the time--everyone will sing along. You can't help it.
Whenever I'm in a rather Yee-Haw place, and bars are filled with folks wearing camo and baseball caps, my go-to is Wagon Wheel by Old Crow Medicine Show, it gets people riled up.
Later in the evening, once folks have had a few drinks in them, Take Me Home Country Roads is unquestionably the song to end with.
Halfway through there's a drunk woman and her reluctant husband/boyfriend/male friend/drafted stranger who sings "Picture" by Kid Rock and Sheryl Crow.
I know someone who did that who is a REALLY GOOD, like pro level singer. Crowd was delighted when she started singing and they heard how great her voice was. Then they were slightly puzzled when some of the words were different. Then they realized she was singing a parody and they were like WTF. I suppose I'll try it anyway if the occasion comes up .
Here she is singing a Queen--Bohemian Rhapsody / Star Wars crossover parody:
If you want a fun karaoke night, first song(s) need to be something that will get most everyone singing. Younger crowds: something like Tayor Swift "Shake It Off". Middle age crowds, something like Nirvana or Aerosmith. Older crowds any Beatles #1.
I personally like Cyprus Hill "Jump Around" if you're willing to learn it well enough beforehand as to not butcher the lyrics. I've seen Vanilla "Ice Ice Baby" also get a similar reaction of everyone knowing the song and enjoying it enough to give you kudos for choosing it.
After everyone's over the initial hesitation, go belt all your love songs and power ballads; but get the party started first.