Personally I don't like any of the maps for this game
I think you want a map which allows all 18 (?) players to fight each other. No one will learn much or have a great time lurking around at the back. Everyone, if possible, needs a front line.
The maps chosen while nice for ordinary mp or sp play don't fit this. They have too much sea which will stop people getting at the other side (Ogre is especially bad for this) or have constricted fronts (Symetry & the Geometry ones especially). Cleveland's Map (Map 3) is best but I think is inferior to simply making a random map with our set up.
If we make a random with very little sea (say 5% or less) for say 360 provinces at 1600*1600 pixels (so square) you should get a decent set up. These are easy to create.
We could then set up the 6 vets in a line east to west in the middle. With a line of 6 noobs close to the North edge (but not right on it) and 6 more in the same position in the south. You would get a map looking something like this:
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXxXXXXXXX
X 6 Noobs here XXXXXX
X XXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
X 6 Vets here XXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
X 6 South Noobs XXXXX
XXXXXXXXXXXXXXXXXXX
XXXXXXXXXXXXXXXXXXX
With each X being roughly a column of provinces (19*19 = 361). PS it's really square
This would give the noobs only a small amount of safe space behind their capitals so they have to expand towards danger (the Vets). The Vets have no safe space but lots of expansion room. This way the edge advantage is lessened as there is little safe hinterland that only the edge powers have. Plus the powers don't meet straight away allowing for expansion.
This enables everyone to get to at least some enemies by walking. It also gives plenty of strategy options. The Vets can perhaps shield the south 6 with two while sending four north. Or spread equally each way so they can all attack or defend in either direction. While no noob is stuck at the back the noobs could shield weaker powers somewhat. And at roughly 19 provinces wide all sets of six work out nicely with the capital and all surrounding provinces being available - everyone gets that - then expands north or south (or both) but not east or west initially. You could zig zag the Capitals if needed but I am not sure this is desirable.
Even though 20 per player is a little large these games are unlikley to drag on very long on past experience and so will end before late game micromanagement hell decends
Obviously it's best if we can get a neutral to build the map and place the capitals. But we can even use the set up without. I (or someone) makes the map and places the 18 capital locations. Then sends the map to the opposition to check that the Capital placements are reasonable and what was decided. Then, after nation selection, the noobs announce the (say) northern 6 noob powers locations east to west. Then the Vets put down their six in whatever order they like (knowing the 6 northern locations). Then the noobs declare the southern 6. So neither side can guarantee fully the match ups they like.
Anyway if you are really sold on those 5 I think Cleveland's map is best for this one game. But a random is best of all. Whatever we play we have to find someone (or some method) to place the powers. Unless you want to go random which is likely to marginalise some powers into spectators (and turn others in to doomed surrounded victims) on set up
