Posted in a guild thread today; "Emperor Tim: May I add, I hate all that is LMA.... It's just a bad age....."
Not to mention HMA and CA are both 3x2 supply buildings while LMA is 3x3 or 3x4.
The point is that in LMA you have 2 recurring quests. HMA and earlier you only have 1.
As you progress in ages, you have the advantages of having more space, and that the rewards are better (goods are of a higher age, and the base number of medals higher). The coins and supplies you get as reward are also higher, but this is offset but the fact that unbirthday and gather X/Y supplies/coins are also more expensive.
Also the supplies production per tile is better for higher age buildings; but on the other hand the cost of the unbirthday quest increases, and the supplies needed in the 'collect X supplies' increases too steeply (increase much more than the increase of efficiency of the production buildings themselves). In BA with a high enough LoA I could collect from 2 blacksmiths and complete the "gather 1500 supplies". In LMA needs to collect from 4 buildings to complete it (Loa lvl 7) and in CA from 14 clockmakers to complete it with Loa lvl 8. (because also the clockmaker is small hence produces less in absolute terms (although more per tile).
And after CA the main problem is that you need to collect 4 (instead of 2) 24hr productions per quest, and from PE onwards 5. So CA is the last age where you can do questing efficiently. Maybe you can do a little in IndA (at least it asks for 4 productions instead of 5) and the gunsmith happens to be small (but you need to collect from 16 gunsmiths (LoA lvl 10) to complete 1 "gather 150,000 supplies".
Other considerations: the more supply buildings you have the less chance all of them will be motivated. Also LoA only applies to the first 40 collections (so if you have more than 40 supply buildings the rest of the collections will not be boosted by LoA, giving you less supplies to use in the [more expensive] unbirthday, and making it more difficult to complete the 'gather X supplies' in parallel with the 24 hr collection.
Also it depends on personal preferences, how fast you want to progress through the ages, how much patience you have for the constant cycling through quests etc. CA is the more efficient age to do questing, but which is the next more efficient I think is a toss-up between HMA and LMA. (Btw BA is also very efficient if one is willing to do a lot of clicking. Look at Glarg's guide for details; also one can do the recurring quests of recruiting units there, which by far the most efficient if one is willing to sit by and click away every 1hr).
for example in 84 tiles one can have
HMA (1 quest only): 14 Alchemists, so 7 quests
LMA (2 quests slots) 4 breweries and 4 cooperages, 2+2+2= 6 quests (the last 2 is the combined quest of collecting from both)
CA (2 quest slots): 14 clockmakers, so 7 quests, + 1 gather 110,000 supplies (LoA lvl 8 needed), so 8 quests total.
So LMA 6 quests vs HMA 7 quests, but the rewards give more medals in LMA and LMA goods are more valuable than HMA goods. Also you have 4 quests in play to cycle through (so much less clicking) compared to 1 quest (collect from alchemist), so that last point to me was quite valuable.
CA 8 quests vs LMA 6 quests, and CA rewards are more valualbe, so CA is better. However CA requires more clicking (so it is up to each person how patient they can be), and also the high number of supply buildings comes into play (whether all will be motivated, and only the first 40 get LoA boost. So the plus 1 quest, will not apply as above after the first 40 collections.)