All mass resource gathering tends to revolve around using recurring quests combined w/Chateaux Frontenac... That Great Building rewards a bonus % of the base reward every time you complete a non-event quest, including boosting diamond rewards!
Best aim is to ask your guild for help in obtaining the BP's + goods to build one, and then level it up to Lv10 ASAP to gain 150% boost to ALL non-event quest rewards.
From there, every level you add to it will increase this bonus by an additional 5%/level up.
Otherwise, the 'best' sources for the various resources would be:
Coins - event buildings, Chateaux Frontenac (CF), Cathedral of Achen (CoA). (St.Mark's boost honestly isn't needed at all)
Supplies - Lighthouse of Alexandria (LOA), Himeji Castle (HC), basic production buildings w/"complete 2x 24hr production" recurring quests.
Goods - Shinto Temple (complete Japanese Cultural Settlement 13 times), Galata Tower, event buildings, CF-boosted recurring quests.
Medals - Lv80+ Arc
Forge Points - Cape Canaveral (CC), Castel del Monte (CdM), event buildings, Cultural Settlements evo buildings.
**Himeji Castle & Space Carrier:
These are special case great buildings that give a % chance of obtaining a reward after your first few battles (HC) or negotiations (SC) every day... within the reward pool is the chance for things like 200 random goods or various amounts of fps (ie: 25/50/100 fps)
Thus, if you're active in say the weekly Guild Expedition and/or the Guild Battlegrounds, these buildings can also become yet another source of goods/fps, though they are of course less reliable than the staples like CF boosted rewards + event buildings.