In my personal experience, these units are a good choice for a team:
Soren (caps mag, res, skill, maybe spd)
Jill (str, def, skill, maybe spd)
Mist (just to have a valkyrie healing and attacking greatly with magic swords, mag, res, maybe speed)
Elincia (mag, maybe spd)
Zihark (str, spd, skill)
Mia (skill, spd)
Must include in a FE 9 team:
Ike (main character, so yes)
Boyd (caps pretty good stats)
Oscar (the same case above)
Rolf (far better than Shinon, therefore best archer)
Marcia (same as Boyd and Oscar, capable of capping some stats)
Nephenee (simply a good offensive/defensive unit)
Volke (best thief/assassin in the game)
As for armored knigths, well Gatrie and Brom have their own growth and benefits, choose the one you like the most. If you won't play RD (which I can guess because you said you would search for an emulator)then don't lose time training Sothe, he ends up pretty limited in comparison to Volke. Laguz are good too, so choose one if you like them. All previous recommendations are based on my experience, so they may turn a bit different.
Also because I guess you're a fan of Kieran, I would recommend him. He's a decent enough unit, worth training. Good luck and hope you like the game. Train a balanced group as in other FE games (tanks, attackers, defender healers, etc) and hope a certain battle in the game doesn't get on your nerves like it did with me. Sorry if I spoiled anything.
Keep in mind the difficulty changes the exp, so if you play in normal (which I do) I would suggest you to train up to 10 units for them to end up begin useful. I would look here for more details.