What would they be interested in, in terms of personality, looks and interests?

5697889 Applejack would like an honest, hard working stallion that can mix work in with their relationship

Pinkie would like someone with the same level of randomness and good will as her

Rarity would like someone who could be her "Knight in shining armour" and tend to her, but would still want to be treated fairly and has some assertiveness

Twilight would like someone who could keep up with her in terms of intelligence, perhaps a scientist, some kind of intellectual but still has enough of a playful side to him

Rainbow would want someone who would sit through her boasting and keep up with her on an athletic level at least, with a wild and adventurous side to him

Fluttershy would like someone calm and collected, good with animals and would help her overcome her shyness

5697893
What you said

5697893 Basically, what he said.

5697893 Basically, what he said.

5697893 so pretty much they rule 63 selfs.....

I'll name the stallions that the Mane Six would like, based on your statements;

Fluttershy: Discord, because he's helped her deal with her shyness and fears, also he's an absolute gentle colt towards her! #Fluttercord-is-Best-Ship

Rarity: I think Fancy Pants would be a good match, because he treats her good, unlike Blueblood!

Pinkie: Cheese Sandwich! Obviously!

Rainbow: Soarin, because he's a Wonderbolt with the same level of athleticism as she has. Also she's saved his behind several times.

Applejack: This might sound weird but I think Spike would be a good option. He's always helpful and hardworking with Twilight, so why can't the same be for AJ

Twilight: I don't know, maybe Flash Sentry. But if Twilight doesn't like guys, I think Sunset Shimmer would be an option

There you have it!

Rarity wants romance more then anything else. Kisses, cuddles,candlelight dinners, ect.
Pinkie wants fun more then anything else.
Rainbow wants someone as strong as her.
Twilight wants someone with a great mind.
Fluttershy wants an animal lover.
Applejack wants someone who will work as hard as she does.

5699821
I can see all of that, save I can see twilight with sunset simmer or luna, or even gender bent luna or gender bent sunset simmer.
I can see applejack with some hard work cow pony or with that pie love wonderbolt