Just to get a general feel for things (and perhaps help guide less experienced players), I think it'd be worthwhile to discuss what we feel are the best and worst of the Age 54 changes. Just to get the ball rolling:
Attackers:
Hands down, Orcs will rule in Age 54. 9-point Elite (which trains with Credits) and +20% Gains make them downright devastating in and out of war, but the real kickers are losing the -10% BE and gaining Reflect Magic for extra defense against offensive Spells. While the penalties to Magic and Thievery were increased, they only affect offensive damage - which most Attackers aren't concerned with anyways.
Though Undead remains a strong contender, the harsher Science penalty and losing War Spoils (negating their Ambush immunity) make them far less desirable next Age. While Plague, No Food, free upgrades to Elites, and 50% offensive losses are still great attributes for an Attacker, Orc's gains, Spell Book, and lack of Science penalty trump Undead.
Dwarves got a much-needed boost (improved Elite and losing the TpA penalty), making them viable Attackers once more. Though their BE bonus was reduced to +15%, it remains a boon in light of high Draft rates. Furthermore they retained their Free Construction and Using Credits to Raze abilities, virtually eliminating all expenses to land management and making them the easiest Race in the game to rotate strats with. No land management expenses also frees up loads of cash to invest in Sciences and Military (or extra Mercs), Quick Feet is almost as good an Attack Time bonus as Tactician, and Clearsight gives them extra defense against enemy Thievery.
Tactician is one of the best options for Attackers - Orcs in particular, as they can use the extra 50% credits for more free Elites. The -15% Attack Times combined with 20% Rax (@90% BE) give Orc and Undead 8-hour Attack Times in War - or Dwarves (w/Quick Feet) 9.2-hour Attack Times with no Rax at all! The 100% accurate intel during War allows them to optimize their attacks, avoiding bounces and potentially allowing an additional attack. By far the best option for anyone anticipating fast, steady growth.
Despite losing the +50% Honor bonuses and casualties modifiers, Warrior gained an extra General to turn it into something of a juggernaut! The +15% OME stacks with Honor, Wages, and TG bonuses (plus the extra General) for an easy +25% net mod to OME in War - making it easy to bust even the most robust of turtles. Excellent overall offensive Personality, in and out of War.
Cleric lost the extra General, but gained a permanent Animate Dead effect - making them all the tougher to chain down. The 50% casualties makes for a strong economic modifier, eliminating the need for Hospitals and reducing troop expenses. Not much to offer growth-wise, but still a solid choice for a Province in a Kingdom serious about War.
Even with the nerfs, Sage remains a solid option for most Attackers. +30% Science Effects give a strong boost to Alchemy, Tools, Housing, and War Sciences. Though Crime and Channeling are of lesser importance for Attackers, modest investment in these gives excellent returns to help protect against hostile Spells and Ops. With War Wins now awarding 100 Books per Acre, the extra +30% Effect becomes an even stronger incentive for those who actively war.
Hybrids:
Faery pretty much goes without saying. Though their WpA and TpA bonuses were reduced, they gained damage bonuses to both disciplines as well. The NW of their Elite has been lowered, giving them a bit more RPNW protection, and the 3-point Ospec makes it easier to stockpile Dragon Chow without seriously inflating their overall NW. Losing Meteor Showers hurt a bit, but the +50% duration mod for Mystic makes a worthwhile option in regaining it.
By retaining their 6-point Dspec and gaining +50% WpA, Elves are even better as Mage/Attackers. Though their Elite shifted one point from Offense to Defense (a 14.3% reduction), their 20% space-saving offered by their Dspecs (as well as the +50% WpA) allows enough space for Elves to be viable Attackers.
The +30% Spell Damage bonus Dwarves received, combined with their BE bonus and no land management expenses, make them viable as Attacker/Mages. In essence, most of Elf's Age 53 traits migrated to Dwarf - 7/3 Elite, +30% Spell Damage, and Clearsight - making them nearly as strong as Elves were this past Age. Not super, but reasonably formidable.
Avians lost a lot for Age 54 - their Dspec lost 1 point and their Elite lost 2 DP, as well as losing Clearsight and Fanatacism. Mystic Aura grants some resistance to hostile spells, but it's a one-shot deal - so not great unless your activity is near-hyper. On the plus side, the OpNW of their Elite is now second only to Orc and Undead - unfortunately, the loss of their 6-point Dspec makes it difficult for them to run enough Thieves to take advantage of their +40% Thievery Damage modifier and still maintain respectable offense. Viable, though by far the most difficult hybrid to pull off.
With Meteor Showers now being Mystic-only, Mystic is a must-have for at least several Provinces within a Kingdom. The +50% Duration offers beautiful synergy with the +WpA bonuses for Faeries and Elves, as well as with Faery's or Dwarf's +30% Spell Damage.
Despite the changes, Sage remains one of the best Personalities for Hybrids - offering tremendous and relatively inexpensive boosts to both Magic and Thievery in addition to the +30% Effectiveness to other Sciences. Again, the new rewards for War Wins combined with the increased Effectiveness bring the net effects up almost to par with how Sage was this past Age.
Rogue remains relatively weak for any except a Pure Thief, though the Double TDs effect can make Avian Rogue a viable A/T. Still a respectable option for Faery, with the +Stealth Regen combining well with their +TpA and +Damage.
The Misfits:
Humans don't have much going for them in Age 54. They've lost their Income bonus and reducing their Elite to 5/5 makes for one of the hardest nerfs to come about. Their +50% Damage with Spells and Ops appears nice, but it'll be a challenge for them to maintain sufficient WpA and TpA to truly take advantage of them. The only thing they really have in their favor (apart from their Spell Book) is their 6-point Ospec - offering the least expensive and highest OpNW option for any Attacker. Even with the +10% Population, they'll be hard-pressed to do more than fill a single role - despite having bonuses to all three.
Losing their Population Bonus and 100% Intel while retaining their Birth Rate Penalty has pretty much eliminated Halflings from consideration for anything apart from Super-Thief - which is useful for a Kingdom, but they rarely need more than one. At least they gained +50% TpA, though this is the main consideration which keeps them from being a complete write-off. This might be enough space saving to still allow them to run Rogue a/T or Warrior A/t, though they'll most likely be weaker in this role than they've been this past Age.
Just my view on the matter, for what it's worth. I'm sure others have quite a different perspective on the options for Age 54.