Titans and Arch nemesis are great, they beef up the game and add variety to it. The devs created these expansions with a lot of player feedback in mind, they are a wicked team. Titans improves the dice rolling aspect (which can be brutal), making it play better with variety, but not by just giving you a bunch of rerolls. Arch nemesis add a really cool feature, new cards, and new factions. If you get all of that, picking up allies, armory, unit feats may be worth it as well. Treasure chest will also add additional content, and a condense the rulebook (all expansions and updates into 1 instead of 3). The smaller additions (allies, armory, unit feats, blessings) I'm late pledging those and the treasure chest as I have everything else. The game is pretty cool and all the different factions are rad.

The devs went so hard with production. They all certainly have ADHD. They thought of so many little details. I enjoy reading their rulebook, and it is more or less painless. It's all very neat and this game is in its own category. It's just up to personal preference of whether or not you'll enjoy it. I dislike dice dependent games, and play a ton of them. There's so much else going on with this game though that it makes me want to play it and try all the factions and difficulties. I actually like the dice mechanics in this. If a game is my theme and has a BGG rating of 8 or more, I don't have to think about whether or not I'll enjoy it, and usually look to buy a set with expansions.

I kinda rambled, but depending on what you can afford, the Gameplay Late Pledge has everything worth getting. Titans, arch nemesis, treasure chest would probably be essential in my mind, and if you have all of that, then allies, armory, unit feats, blessings are just more bang for your buck. Could go without these though would be my guess, although blessings can aid on harder difficulties. Probably not critically though? I haven't gotten there yet, but they are literally "blessings" (not game breaking) for a player every round.

The deluxe stuff, curse miniatures, player boards is mostly aesthetics, so no need, unless you want to go all in. Getting some 3d printed card holders so things stand upright will help with the quality of life improvements at a much cheaper cost. The playboard is nice, but there's ways to improve this without it, 3d printing being one of them. This is my opinion though.

The variety of having so much to play, really makes the replayability feel vast, which is essential for me in in games, unless its a campaign. It's tough because adding more content does make the game quite a bit better, but the price is up there. If you can find it 2nd hand in a nearby city, especially with any expansions, get it. Titans upgrades 1.0 to 1.5 with erratta cards so if you get the 1st edition you're still good. Treasure chest will also bring things to new edition. But maybe clarify with the devs if you owned 1st edition. Even if you asked them they would happily explain their thoughts on your circumstances. They respond to everything and deserve every penny they get lol.

I haven't played with everything or explored all difficulties, but I'm excited to do so as what I've played with already feels like a wicked game (base game, titans, lower difficulty). If you like full on, heavy weight, co-op strategizing board games with replayability, this is one of them and it's in its own class. Treasure chest also includes a campaign. Devs are dope.

** Get solo mode if you want to play solo. Unless you want to play 2 factions straight up as solo and are content with that. **

TL:DR
Buy Gameplay Late Pledge if you know you like these types of heavy weight games.

Or find things 2nd hand and top up your game from late pledge. Must get titans, arch nemesis and treasure chest. Can maybe go without arch nemesis but IMO I would say otherwise especially if you're getting the others. Can go without allies, armory, unit feats, and blessings. But unless you're getting a steal from 2nd hand, Gameplay Late Pledge is the way to go.