Style is the first thing we ask about, and it is the decision that changes the most. The same words can arrive as a lump in the throat or a room full of people dancing badly. So it is worth thirty seconds of thought.
The good news: you are not picking for you. You are picking for them, and you already know what they put on in the car.
Acoustic and heartfelt
Warm guitar, close vocals, nothing in the way of the words. This is the one that makes people go quiet, then reach for a tissue and pretend they are fine.
Pick it for: parents and grandparents, anniversaries, the sentimental one in the family, anybody whose reaction you secretly want to film.
Upbeat pop
Big chorus, proper drums, the kind of thing that gets played twice in a row. It carries a room, which matters if the song is going to be heard at a party rather than alone on headphones.
Pick it for: milestone birthdays, best friends, teenagers, anyone who would be mortified by a slow ballad.
Country
Storytelling with a wink and a fiddle. Country is the most forgiving style for detail, because the tradition is built on specifics: places, names, the thing that happened that one summer. If you have a lot of story to give, this one holds it.
Pick it for: long marriages, dads, road trips, the family that has a lot of history and enjoys retelling it.
Piano ballad
The most emotional room on the list. Space, patience, one voice and one piano doing the heavy lifting. Handle with care, because it is not subtle about feelings.
Pick it for: weddings and first dances, big thank yous, the moments you want people to remember for years.
Rock
Guitars up, gravel in the vocal, nothing precious about it. Rock is brilliant for the person who would find a sincere gift excruciating, because the joke and the sentiment can sit in the same song without either winning.
Pick it for: the sixtieth that is being treated as a twenty-first, brothers, mates, anybody with a leather jacket they still wear.
If you are torn between two, go with the one they would put on themselves, not the one you think suits the occasion.
Genuinely not sure? Choose Surprise me
It is not a cop-out, and plenty of people pick it deliberately. Choose Surprise me and the style gets matched to the story you tell us, so a funny story about a chaotic dog does not end up as a solemn ballad. If the story is tender, the music follows. If it is daft, the music has fun with it.
Then there is the mood
Style is the sound. Mood is the feeling, and the two combine rather than compete. The same acoustic setup can be emotional or playful depending on the mood you choose, so if you want warm-but-not-weepy, or funny-but-with-a-real-line-at-the-end, that is where you say so.
The safest way to decide is to hear a few. The free song library has thousands across every style, all free to play. Find one that sounds like them, then start theirs. And remember you get to read the full lyrics before you pay, so nothing is locked in until you say so.