Champion of the Parish: In my opinion the most powerful human in modern magic. Usually he swings for 3 damage on turn 2.
Kytheon, Hero of Akros
: 2/1 body for 1 mana that becomes a Planeswalker eventually. I think that is pretty neat.
Boros Elite
: Goal is to attack with a 3/3 at least (best case with additional counters on it as well as with first strike). Still have to play test it though.
Thraben Inspector: I often find myself empty-handed after a few turns. If my opponent plays enough removals or drops a board wipe, it's pretty much game over. With this beauty I managed to keep some cards in hand and regrow after a board wipe.
Thalia's Lieutenant: Extremely powerful human and has a very nice synergy with Champion of the Parish.
Thalia, Guardian of Thraben: Slows down the opponent. Casting a Path to Exile or Fatal Push for two instead of one mana makes quite a difference (although I have to keep that in mind too if I want to get rid of his blockers with a path).
Metallic Mimic: Gives the entering humans an additional +1/+1 as well as triggers Champion of the Parish and Thalia's Lieutenant. Only drawback; he doesn't get the soldier anthem from Field Marshal (if I choose it to be human of course).
Field Marshal: The lord of this Soldier/Human deck. The First Strike really gives a much appreciated advantage. Only (and admittedly a small) problem: Every soldier gets the anthem, not only mine.
Thalia, Heretic Cathar: This is pretty useful since potential blockers enter the battlefield tapped. In addition, it slows down the opponent due to the nonbasic land effect.
Ranger of Eos: The cost of 4 mana might be quite high, but we can get two Champion of the Parish out of it, I think that's a good bargain.
Spells
Path to Exile: This removal is pretty much needed in order to get rid of nasty blockers or huge creatures.
Return to the Ranks: I just recently added this card since I faced an empty board many times due to wipes or lots of removals. If you can get 3 - 4 creatures back with it, that is very useful, especially if you get some Champion of the Parish and Thalia's Lieutenant.
The Sideboard
Blessed Alliance: Very versatile card and useful against several different match ups.
Collective Effort: Not a bad card but still not sure. The escalate cost are reasonable and the modes are quite nice.
Disenchant: Definitely boarded against Affinity but also against some decks with nasty enchantments.
Kor Firewalker
: Good guy against burn decks.
Rest in Peace: Good against a deck that uses its graveyard, e.g. Dredge or some control decks with Snapcaster Mage.
Selfless Spirit: Very useful against sweepers or removal such as Fatal Push.
Stony Silence: Obviously against Affinity. If the opponent has no SB cards to get rid of it, the game is pretty much over.