Darkstone (100 gold), Karakoth (50), Blighted Lands (25), Silverglade (25), Zul’Kari (0) are almost always prioritized for MAGIC.
[At Kingdom Level 10 you will get +1 Magic for all your troops, all the time! This is unrelated to Home Kingdom.]
Whitehelm (0) is often prioritized as Home Kingdom for the GLORY.
Khetar (0) is sometimes prioritized as Home Kingdom for SOULS.
[Pick one or the other, do NOT prioritize both!]
Once you have decided your initial priorities, you should level ALL YOUR OTHER KINGDOMS in order of gold Return On Investment (ROI).
That is to say, how much do you EARN versus how much does it COST to level the Kingdom?
The greater the ROI, over time, the faster the Kingdom’s new level will pay for itself.
The faster it pays for itself, the sooner you can afford to level the NEXT Kingdom.
Over time, buying Kingdoms in this order will snowball into getting ALL Kingdoms to level 10 faster than buying them haphazardly.
Although this method requires some long-term thought and self-control, it is the best option to obtain all Kingdoms at Level 10 in the shortest amount of time.
1st number is the gold TRIBUTE value.
[For example: 250 is Khaziel with 250 gold tribute.]
Number in (parentheses) is the NEW LEVEL of the kingdom you are purchasing.
[You should buy all Kingdoms at Level 1 regardless of Gold value.]
Priority 1 250 (2), 200 (2), 175 (2), 150 (2)
Priority 2 250 (3), 200 (3), 175 (3), 150 (3), 125 (2), 100 (2), 75 (2)
Priority 3 250 (4), 200 (4), 175 (4), 150 (4), 125 (3), 100 (3), 75 (3), 50 (2)
Priority 4 250 (5), 200 (5), 175 (5), 150 (5), 125 (4), 100 (4), 75 (4), 50 (3), 25 (2)
Priority 5 250 (6), 200 (6), 175 (6), 150 (6), 125 (5), 100 (5), 75 (5), 50 (4), 25 (3)
Priority 6 250 (7), 200 (7), 175 (7), 125 (6), 100 (6), 50 (5), 25 (4)
Priority 7 250 (8), 200 (8), 150 (7), 75 (6)
Priority 8 250 (9), 200 (9), 175 (8), 150 (8), 125 (7), 100 (7)
Priority 9 250 (10), 200 (10), 175 (9), 150 (9), 125 (8), 100 (8), 75 (7), 50 (6), 25 (5)
Priority 10 175 (10), 150 (10), 125 (9), 100 (9), 75 (8), 50 (7)
Priority 11 125 (10), 100 (10), 75 (9), 50 (8), 25 (6)
Priority 12 75 (10), 50 (8 - 9), 25 (7 - 8)
Priority 13 25 (9 - 10)
Priority 14 0 (2 - 10)
Gold Kingdoms
250 Khaziel
200 Blackhawk, Broken Spire, Stormheim
175 Adana, Urskaya
150 Maugrim Woods, Zaejin
125 Mist of Scales, Sword's Edge
100 DARKSTONE, Pridelands, Suncrest
75 Forest of Thorns
50 Divinion Fields, Drifting Sands, Ghulvania, Glacial Peaks, KARAKOTH, Leonis Empire
25 BLIGHTED LANDS, Dragon's Claw, Pan's Vale, SILVERGLADE
0 Grosh-Nak, Khetar, WHITEHELM, ZHUL'KARI
Below is a more detailed spreadsheet if you want to really maximize the effectiveness of your gold purchases:
https://docs.google.com/spreadsheets/d/1Mw0dycvyGR4-P8judFtlH2PDRSNpafyHyy5iUp48JQA