Hey Brother Trokair, welcome to the open skies. I've played about a half-dozen games now, because it was my friends who were really interested and I just tagged along. I'm basically the friend who'll split a box for a low commitment game ("oh, I just need to paint 5 models? Ok, I'll split the starter with you"). I play Tau (I never collected Tau before, but my friend wanted the Imperials, so I'm playing Tau). Here's what I learned.
+++ What You Need...comes straight outta the starter set +++
Short Answer - everything you need comes right out of the Starter Set, for once. 2 factions of enough planes, that hex grid map, tokens, a cheat sheet, rules, dice.
Longer Answer - I'll tell you what else you should and shouldn't buy, but unlike 40k or AoS where the Starter Set is really just a start, AI is a complete game tbh:
You probably don't need more planes. There's a points system with AI just like 40k. Your games are supposed to be 100 minimum, but can be 150 or 200 max. Here's my honest opinion, 100 points is totally enough. The starter set comes with just a little more than 100 per side (depends on how you arm them with the options on their sprues, etc). Any more and the map board mat will be so cluttered you're knocking each other's planes off their bases, tokens are all over the place. This isn't like 40k where a Start Collecting boxset is really just a basis to start, AI is complete in and of itself...kinda refreshing from GW.
But you probably want to swap out certain planes. There are clearly better and worse options. It sounds like you're probably the AI leader in your area, so you want to create a friendly atmosphere so people try out the game, thus I reckon you're not out to optimise army lists any time soon, so just know there are more optimal options up front. I'll show you mine real quick:

I spedpaint these, 4 Tau Bombers with their long-range railgun thingies. A Starter Set gives you 2. 2 friends wanted to split boxes so I ended up with 4, and having played...these are clearly the optimal planes, at least for me.
What about those Aircraft & Aces army card things? They're so optional as to be completely unnecessary. I ended up using that Battlescribe app, which includes AI army lists now. I bought these not even as a convenience, but as a courtesy, because I thought I'd really customise my fleet with this pilot or that upgrade, and I wanted to lay them all out for my opponent to see to avoid confusion. Instead, what happened was I decided to use multiples of the same aircraft, same configuration, which was the best way to avoid confusion.
As for the hexgrid map battlemat, there's the more solid cardboard version. That is optional, but actually might be a good buy eventually because sooner or later you'll rip the one in the Starter Set, which is like a piece of poster paper.
You asked about the ground asset thingies...you surprisingly might need those IF you play missions where you use the ground asset thingies. Usually only 1 side needs them, like in a bombing run mission it's randomly determined if you're the attacker or defender, the attacker is bombing the defender's ground assets...so it'd be nice if the defender's ground assets matches his faction. I think you can buy them for your actual army list, but I don't think they're very good, but I might be wrong about that.
HERE'S WHAT YOU REALLY NEED TO MAKE SURE YOU KEEP. Not an additional purchase, it comes with the Starter Set: the cheat sheet with the Maneuvers and the Maneuvers Tokens. So you don't just move planes like units in 40k, there's a whole phase where you have to secretly set your Maneuvers. They're numbered, so you have to refer to your cheat sheet to know which one it is, then lay the corresponding Token by each of your planes. This is the most tactical part of the game and is referred to all the time. So you might want to keep that cheat sheet in a folder or laminate it, keep those tokens in a little ziploc baggie.
To recap, AI for once has everything outta the box, maybe you need to buy planes you prefer or the ground asset thingies (they are pretty cute), but most importantly make sure you don't lose the Maneuver cheat sheet and Maneuver Tokens.
+++ What I think is the optimal army list(s) +++
This part is just, y'know, for your curiosity. I don't take this game too seriously, and I don't think it should be played too WAAC competitively.
Here's the winning strategy imho: choose the planes (usually Bombers) with the most "Wounds" (called Structure in AI), with the longest ranged guns, that are just at or under 25 points each. The Thunderhawk may throw this strategy out the window, I don't know, I'm planning to get my own ones soon. Here's why.
Why the most Wounds/Structure? Whereas 40k is a very Objective-grabbing game, AI is a very Kill Points-oriented game. Your planes dying or taken to half-health is Victory Points for the opponent. For Tau, a Fighter with 2 Structure costs 22 points, but a Bomber with 5 Structure costs 24 points...of course you'd want the Bombers. Yes, the Fighter is more maneuverable and stuff, but at that price difference and the fact that Fighters can easily go down before they get a shot off, Bombers seem to be obviously more competitive.
Why the longest ranged guns? It's more than the obvious issue that you can shoot the enemy before they get close. The real reason is to get overlapping arcs of fire. What happens with the Tau Bombers is I spread them out to the edges of the map, with the ones on the side edges turning in. Together, they create this killzone between them. Orks obviously want to get in close with their shorter-ranged guns, for example, where the Tau are comparatively disadvantaged...but Tau don't shoot what's closest to them. Instead, Tau act as Wingmen for one another, using their optimal mid- or long-range firepower to kill the Orks bothering their comrades instead of what's in front of them. Then Orks have to take time to maneuver for another pass if they survive, while my Bombers could take it. I shared my experience with my friend, Tourney Tony in Toronto, and he summed it up perfectly, "Everyone is each other's Wingman...it's the Greater Good." This strategy applies to all factions though imho.
Why planes at or under 25 points each? As before, games are at 100, 150, or 200 points...most planes are between 20-something to 30-something points. 25 point planes means I can fit 4 in 100, 6 in 150, or 8 in 200. That just means more Structure points for my opponent to shoot through...basically all this really means is, I bring the max Structure points to a game, which simply makes it harder for the opponent to win, that 25-point threshold is just how it works out with the way they assigned points values to planes. I use Tau Bombers that cost 24 points and I bought a 1-point upgrade for each. Imperial Marauders are the equivalent on their side. The Thunderhawk is a different beast with a whopping 8 Structure points each, so this might be a game changer.
That's what I've found, anyway. I've yet to lose a game and the MVPs have always been the cheap Tau Bombers with long-ranged guns. I just refined my list over Christmas by splitting another starter set to get more Tau Bombers. Good times, low investment.
Edited by N1SB, 08 January 2022 - 04:32 PM.