I'd like to learn how to play this game better... especially territory selection. Are there any good YouTubers or streamers who play this game at a high level? Preferably someone who explains their thought process as they play. There unfortunately doesnt seem to be much of a presence of this game on any major platforms that I could find :(

https://www.youtube.com/watch?v=QagMmnB88F8&feature=youtu.be

Skip the first hour and turn up the volume for a useful discussion on picks (territory selection as you call it).

here are a number of guides, including some YouTube videos

https://war.app/Forum/688994-strategy-guides?Offset=0

You can find sources here and there, but due to the vast variety of templates on the game, it also needs experience in a sense that you need to have some idea, and improvise based on how it goes. Checking your past games and thinking " how I can improve my picks" is 70% of the story, as once you think about it you can either figure stuff yourself or ask people.

Here is some basics off of my head:
1. Always pick maximum number of picks (e.g. in a 1v1 game each player takes 6 spots, pick 12 picks.)

1.1: If you share some picks with opponent and the game uses "cycle" turn order, sometimes you can figure out move order at turn 1 start.

2. In picks you generally try to balance 2 factors: map coverage vs getting income earlier with putting (some) picks close, and (for some maps) small bonuses vs big bonuses. The 2nd one is a way advanced concept (and I am bad at describing it) so you can mainly focus on the first aspect.

2.1. Regardless of whether you decide to group up or not, it is almost always prefer efficient bonuses. (e.g. if a map uses 5 territory 3 income and 6 territory 3 income, it is better to avoid 6 territory 3 income bonus at picks). Two popular notable exceptions: If you try to use that spawn point to prevent enemy from completing bonus it may be OK to pick inefficient, and in some maps (mostly brawl maps)early income is so important that you may pick even wastelanded bonus spawn to complete bonus fast.

2.2 For finding the optimal balance for picks, you must consider how big the map is and how many teeritories you will own after picks, base income, starting armies on each territory you own/neutrals, time to complete bonuses and the time you expect crucial fights to happen. In general you want to maximise your income when/shortly before crucial fights begin. As an example, in French Brawl template fights may start as early as Turn 1, and games usually end before both sides continue can complete all their bonuses; so picks usually go around maximising income early on OR getting some income early so you can complete some bigger bonuses and survive. In either case using multiple picks to complete bonus is meta. On the other hand, in strat 1v1 template (or medium earth traditional), each side gets 3 spawns in a big map and having 2 picks close do not always speed up the time to complete a bonus, but can lock you out of a region completely. The time for combat/crucial fights can be way later, sometimes end of turn 2 income can be crucial, rarely you can see turn 1/2 contests, but it isnt uncommon to have fights after each side completed multiple bonuses. So although specifics vary from distribution to distribution, it is way less common to combo picks.

There is much more to talk about and as you also probably realised it is a deep sea to learn. I'd say picks are at least 50% of the game, so as I said at the beginning the best way to learn is by making mistakes and then correcting them.