Vice mayor of 2)Size of Extreme biomes:
Well, size does matter, at least for exploration in CoE. A biome with bigger size may hold more resources, and also have more areas for us to explorer. Areas that no one has ever visited simply invite Soulborn engine to add interesting contents. The larger the area for an extereme biome, the more likely this will happen. This is not necessary true, but can very reasonably be the case.
I am not going to discuss size in the absolute sense (i.e. measuring in KM square). Instead comparative size is used: comparing sizes of extreme biomes, to other biomes. This is because we do not have the tools to measue the sizes. The maps provided to us may not be in the same scale. Moreover, the bigger the portion of a starting continent are exterme biomes, the more important exploration is. Imagine if we have 2 maps which only have 2 biome, Taiga and Grassland. Both maps have the same size for the Taiga. However, outside the Taiga, 1 map has grassland 10% the size of the Taiga, while the other map's Grassland is as big as the Taiga. Needless to say, the communities within the map with a smaller Grassland will encourage exploration much more.
I am using Zylas's data, Count Zimmah's google doc's “Area data” as the basis of this analysis. Great thanks to both of them. The biome size is measured in the unit of pixels. I basically award points to each extreme biome base on their size following rule:
smaller than average biome : 2 same as average biome : 3 larger than average biome : 4
Then I just add up the score for each of the 20 map. Maps having a Bog will naturally have an advantage, because I considered Bog to be an extreme biome while salt Marsh is just a diffcult biome. So those maps get at least 2 additional points, even the bog is samll. In short, the higher the score, the better it is.
Results:
Maps scoring 9 or 10 points:
Map A, F, G, H, J, S and T
Special mention: Map J is the map with the least landmass as extreme biomes (19.5% only). In short, the need for exploration here is the lowest.
The following maps score 11 or 12 points:
Map B, C, D, E, L, M, N and O
Notable mention: Both Map C and N have all extreme biomes in similar size. Therefore, if you wish to vote for a map where you can easily find exploration groups each focusing on different biome destination, Map C and Map N are your best bet.
Map D is the only Map has both the swamp and tropical rainforest as smaller than average. I guess this is the clear choice if players wish to avoid dealing with extreme humidity in the early years of CoE. On the other hand, it is one of the few maps having a larger than average Semi-arid desert. If you wanna play a waerd explorer, this map sounds like a good choice.
The following maps score 13 or 14 points:
Map I, K, L, P and Q
Notable mention: Map I is the map with the greatest portion of landmass belongs to extreme biomes (Up to 33.95%). It is also the map with the biggest Taiga biome.
Map K is the one with both a large swamp and tropical rainforest. It is also one of the maps with a bog. This is the map with the largest portion of the treasures hidden in high humidity biomes. Without a doubt, this is the best map for Dras explorers, as long as you know how to survive in a biome where the foodchain is circular.
This concludes the 2nd section of the exploration analysis. Before moving to the 3rd portion, I would like to summarise the results of the 2 previous analysis as both of them focus on exploration before sea-faring technology is possible:
Map L has a large area in extreme biomes, at the same time, its biomes are among the hardest to access. Therefore, it provides the most content for exploration players. This map also has the biggest Bog biome out of all the maps. The best map if you want the most exploration.
The second place is tied between Map K, and Map N for me. Both map's Taiga and rainforest are difficult to reach. It will heavily come down to if you wish to deal with the bog biome. Map K has a Bog while Map N does not. Map K has 33.70% landmass covered by extreme biomes (ranking #2). However, Map N makes it up by having healthy spread of biome size, offering less direct competition.
Map I is the obvious 3rd choice. 33.95% of its landmass is in extreme biome, and the largest biome is the Taiga. If you want to play as a Hrothi or Brudvir explorer, you may even prefer this maps over those I stated above. The Taiga is also hard to access, which means the Brudvir / Hrothi explorers have a head start on the Taiga's exploration.
My 4th map would actually be Map C. Although it only has an average score in both the accessibility and size criteria. One thing I did not mention previously, is that this map has its Semi-arid Desert sitting at arguably one of the most important strategic location : Any one traveling from South to North or vice versa must pass through the desert. Even the rewards lying within the extreme biomes may not be as tempting, this map provides the biggest demand on explorers as guide and pillars for an invading army.
Since we don’t have enough time for a deep analysis, I have to save some time by eliminating some maps from my analysis using the coastline length. Only the top 6 maps with the best biome having the highest total coastline length will be further analysed. Only bays in the best and supportive biomes will be take into consideration. (Bays are circled in white) 
Map E is a very interesting candidate. First off, it is characterised by notable bays in the Sothern continent is far away from the Northern ones. This implies there will be a long period of time that the Northern tribes and Southern tribes develop very different type of ships. 
Map A ranked number three and offers a completely different naval picture from the above ones. In this map, all notable bays lies in the Northern continent. It seems the naval technology will be lead by the Northern tribes. The woodland Savanna does not even has a coastline. 
The landscape of Map S have most of its notable bays most on the Continent's Western Coasts, safe for the one bay in the Woodland Savanna. I can see the Brudvir and Hrothi will compete with the Dras for the control of Western waters. There is also this large BroadLeaf forest Gulf that I do not what implication it has.
Map G and Map H ties in terms of coastal length. Like Map B, The Neran coastal area are located at strategic locations, and also within a gulf. Interestingly, between the Mixed Leaf Forest and the Broad Leaf Forest, the coastline extend into the inland according to the map. Does this mean a River grows wider and wider approaching the sea? I would just say that, River settlement there could very well be developed into ship building a settlement. In terms of naval power, the North will once again see fierce competition between Neran and the Brudvir. It is hard to call who is going to come out on top, as the Neran has the benefit of the Gulf to train in calmer waters but the biome size is smaller comparing to the Brudvir's, offering less resources. 
Map H ties with Map G in terms of Coast length merely because I did not count the inland sea. This inland can be a game changer in terms of sea-faring technology. I have no clue what I should make out of the inland sea though. So my analysis below might be huigely off the mark. In the Northern seas, the Neran and the Kypig are completely separated in terms of naval force. This complicate the naval competition quickly and I can't tell who is on top. The Southern seas is dominant by the Dras once again. Nothing is certain on this map, except the Woold Savanna To'resk are pretty much behind in the naval race. 
