Hello! I think most people would agree that achieving Victory as the Grand Alliance is difficult. I decided to start writing a guide and this will be updated as I find the best courses of action and as a PBEM(I have 4 finished games) game continues.
I think the Grand Alliance can win by min-maxing the resources it has and utilizing everything from generals command points to using navies.
First part is a list of needed elements and brief analysis of the different armies.
Hesse
20 cav (prioritize cuirassiers)*
32 inf
Quality: Cannon fodder
Palatinate
45 cav (prioritize dragoons)
Quality: Cannon fodder
HRE
24 cav (prioritize dragoons)
Quality: Cannon fodder infantry, buy hussars all of them ASAP!
Austria
16 inf
7 cav
Quality: More hussars! Buy them! Very expensive and almost not worth it infantry buy hungarian infantry sometimes if you're facing hard times. Buy imperial infantry first in Bohemia-Moravia.
When more HRE and British-Dutch unlocks:
Brunswick
18 cav (prioritize cuirassiers)
Quality: Cannon fodder
Hannover
28 inf
50 cav (you have a lot of possible full cuirassier regiments here, build them up when you have money)
Quality: Cannon fodder but a potentially huge amount of heavy cavalry
Dutch
102 cav this number is so massive I would merge all the understrenght dragoon regiments and leave the cuirassiers resting and prioritized in Amsterdam and Breda until they are full.
8 inf (Coenders Company missing 4 and De Muralt missing 4 important to replace!)
Quality: Best bang for pound and men here, you've got the Swiss, Swedes, Huguenots and Germans so buy them all before anything else. Schomberg and Sparre can be attached to Imperial armies to negate CP malus from these mercenary units. Buy marines later. Ignore fusiliers and grenadiers.
English and Irish
57cav (prioritize cuirassiers)
Quality: High, long build times, buy the Irish regiments first, then marines. Ignore fusiliers and grenadiers.
EDIT: British guards are the best guards GAL has so try to use them wisely.
Scots
All elements present
Quality: Cannon fodder, buy in case of an invasion to either Scotland(Inverness or Aberdeen only) or Ireland as they are quick to build.
EDIT: Slight mistake here. The forces which unlock in the Netherlands are above average.
Decision bought armies:
Prussians
All elements present
Quality: Best troops(if not counting the Swiss), low in number, cannot be commanded by a HRE commander so they need either Eugene or Marlborough. Don't let Wylich-Lottum be in command it's almost a crime!
EDIT: Prussians are still better than fresh Swiss because they have superior maximum cohesion, they just have less staying power in combat but are much better at fighting after a march.
Danes
All elements present
Quality: Better than generic HRE and you get a lot of them, Reventlow needs an Austro-German Commander helping him.
Portugal
2 inf
Quality: Worst line infantry in the whole game, light infantry is very good and you get a lot of them so I would buy all of them if you want to commit in Iberia. Small navy, free ships is not bad.
More coming later
NOTE: Quality isn't essentially completely based on combat power. For example the Danish regiments have 75 combat power and 80 max cohesion so they are better than some veteran troops with a 75 max cohesion after a march or a fight if there are multiple fights.
* Prioritizing means putting these troops in green-green mode and best of all detached from the main army as they are prioritized for replacements.
Why prioritize? Hessian cuirassiers are likely to fight in clear terrain in the north, Palatine and HRE dragoons in difficult Rhine frontier terrain and Brunswicker+Hannoverian cuirassiers against the Bavarians in the Bavarian clear terrain.
As a general army building guideline, I would say 2/5 to 2/6 should be cavalry with a mix of heavy and lighter cavalry, remember that heavy cavalry is almost useless in marshes and moors, artillery is a bonus.