The most important thing will be to have a fast CPU since the game will be at it's most critical point when there are hundreds of troops on the map at the same time (especially with mods which usually increase the number of available troops).
And the fastest CPU for gaming (for a reasonable amount of money) is an Intel Core i7 7700K for roughly 350 Euros (skip the K version if you aren't interested in overclocking the CPU and you might save 50-70 euros).
And to go with that, the GPU would be a GTX 1080 for about 600 Euros. An alternative might be the new AMD GPU coming out soon, Vega RX 64 for about the same price.







