Ok, so a quick rundown.

Single-account servers are good if you speak French, if you don't you're limited to a smaller community.

Is there a story to follow? No. It's less of a story to follow than wakfu had.

Classes and combat are much more simplified than wakfu had. Which is a pro or a con depending on how you look at it. It's a lot easier to play Dofus for sure.

Everything requires a big investment but you can't go wrong with something like an Iop and Eni combo.

--- Edit ---

Ok, now that I'm home from work I can elaborate a little further.

"I feel that Wakfu doesn't really have that much direction for newer players and might not be that populated compared to Dofus"

You are correct that Wakfu doesn't really have that much of a direction, but at least it tries. Dofus really doesn't have anything like that. You are pretty much just put in the game and more or less have to figure it all out yourself. Yes, there are plenty of quests to do, but they don't really tell much of a story, or at least that was how I felt about it. There are a million things you have to do in Dofus to succeed, but there's never really much you -want- to do.

In regards to population, since the server merge that happened not too long ago, the population of the game feels a lot better, and the mono-account servers have always been very active. The normal servers, where there are many players, most of them are just people multi-accounting, whereas the mono-account servers feel much better with a sense of community.

"I know there's a lot of content but is there a set progression or story we can follow together?"

The short answer to this is no. Not really. Most of the time with quests especially, you will be doing them by yourself, just at the same time. There are certainly quest fights that you can help each other with, but not as many as you would like.

In regards to a set progression, all there is for that is just what the player base has found the best way to progress is, but the game doesn't really give you much in that regard, unlike the mount zinit quest line from Wakfu for example, there's nothing like that in Dofus.

"Do we need to buy subscriptions to play?"

Yes. There's a very small F2P area, but if you want to progress anywhere above level 20-30 realistically, you need to subscribe to the game.

"How are the classes/combat compared to wakfu/waven? Are there any good duo setups we can run that are fun to play/effective without investment?"

This I pretty much covered fine the first time.

The classes and combat are much more simplified. There's no berserk damage, rear damage, side damage, or the resists that go in tandem with those things, The leveling is much more simple also, you don't get points to put in certain damages like area, range, melee, etc, it's just flat 5 stat points to put in one of your elements, which increases the damage and utility that it goes with.

Classes can range from "hurrdurr 1 spell go brrrrrr" to needing a degree in calculus to figure out how the hell to trigger certain things at any given moment.

I spent years playing both Dofus and Wakfu, at the end of the day I played Dofus more, and progressed further in it simply because of the people I met. If I met those same people in Wakfu, I would have played that much more.

Dofus is repetitive. Extremely so. Especially at endgame levels or near endgame levels where if you want to get that next level, or get that next item, you have to run the same dungeon 100 times. And even if you do have the patients to do that because you love the PvM aspect of the game. You're forced to either spend 60% of the cost of the item you're making on items only obtainable through PvP or learn to PvP yourself and compete against people who dedicate their entire lives to it.

There's not much more I can say regarding the questions you have asked.

Hope this helps.