HoI3 is where they went, most probably. The fact that a game is the most popular does not necessarily make it the best one, though.
I understand it needs Semper Fi, and would add that.
Frankly, I'm quite disappointed with AoD because my expectation was it would be an improvement on HoI2 DD which I played for about 5 years, loved it, but was looking for a game that had the mistakes in HoIDD fixed. I did NOT ever play Armegeddon and so there exists a gap in my ability to relate to this game's evolution. But I find AoD has just complicated things imensely and not even fixed many obvious design problems with the earlier game.
One of the best fixes they did was to provide a button for leader trait "specialty", which eliminates hours of wasted time scrolling for that last logistics guy. But - just one example - they never fixed how convoys need to be managed and how the different displays for convoys and supply depots need to interface so they can be properly micro-managed. Instead they enhanced it to now include also representing the convoys needed for trades, but work them differently. And these "trade convoys" now completely muddle any human ability to even manage the old supply convoys. The enhancement (let's also show the convoys needed for trades) destroyed the old game management of supply convoys. A good expansion would have keep the old supply convoy idea, fixed the interfaces for supply depots and convoys (so they were shiftable like one can move builds up or down in the queue listing), and introduced a new enhancement like they did which is ability to draw supplies from nearest provincial depot (instead of the capital). As regards supply convoys, that would have opened up the sensible fix of (USA player example) stockpiling in Hawaii, and specific supply convoys from Hawaii running short distances to further islands bases, instead of every supply convoy goes from mainland USA to island base. If the game had gotten that concept right, and AI taught how to use it properly, the next game would have fixed something that mattered. But instead they decided to enhance the game (read "to complicate it") by adding trade conveys now running like supply convoys without fixing the old convoy management problems. While micromanagement of convoys was challenging before, I think now it is pointess to even try.
Baiscally my criticism is that the game adds so much new stuff that is prone to new bugs and new design failings without ever having really fixed the obvious flaws, bugs and design failings in the old game. For instance, ships going to Manila still travel thru land to reach Manila port. While I am all for improving the AI, game development should have been a logical "fix the bugs" like the old ghost fleets", change the errors in map so ships don't cut thru land, etc, enhance the game in small ways to eliminate over simplification of things like the Panama cana (with its beach icon in the wrong ocean)l, and get the AI both smarter while preventing it from doing what everybody was complaining about (stockpling units on useless islands and provinces while leaving an important front empty).
Instead I find AoD to be a radically changed game containing many of past HoI's errors, complicating the playability to a much higher level, and introducing new problems with the many new enhancements. And as regards graphics, AoD is simply downright awful compared to HoIDD. The changes are slight, from opening graphics to the exact color choices for provinces. If HoIDD was vivid, then AoD is garish.
Certainly the game needs a wiki to help new comers understand how sliders and other things interact. How come my spies are killing enemy spies when I have zero dollars appropriated to espinoage activities? Why can I underfund civil expenses by 50% without an increase in dissent? In fact what is the relationship between the new Expenses Section and the old dollars represented in Consumer Goods and daily dollar income inclusing trades? The old system was understandable. One could calculate and see exact responses to any changes one made. Now I feel "quite muddled" by the different interacting sections that no longer seem to add up. Obviously, just let the game play itself on full auto - and go read a good book about WWII. I am sure somebody will retort "I should stop complaining and read the manual". Well, the manual is an outstanding failure - not even page numbers! I did read it all, and it is just the same general mumbo-jumbo of earlier manuals. While it mentions everything and what all buttons do, it doesn't reallly say how anything works or inter-relates. But in the ealier game I could, for example, predict time for a technology to finish. But now I am not even able to figure out why some techs don't advance as they should even with 100% funding. Before things had direct relationships; now there seem to exist nebulous relationships.
The diplomacy sliders work the same. But I don't appreciate the unknown extra influences of National Identity, Social Policy and Culture because I suspect that each are important modifiers to the choices in government and also the annual slider shifts. It becomes a game of "chance" instead of knowing the effects of changes to reach one's focus. And I really dislike being given dissent without advance warning that making a certain political change will give me dissent. It should be part of the information to help me make a decision - not surprise me. The game allows one annual "free" slider shift, righ?. But you can do another one about a week later with a freebee of umpteen more dissent. Of course, bad hard coding like that only results in a new player exiting and starting over. What a waste of time!
While I know nothing about HoI3 with Semper Fi, just the graphics alone make it very interesting. But somehow I think that maybe my biggest problem is that I actually have not played any game since I quit a year ago. Perhaps both AoD and HoI3 are too big a leap coming from HoIDD, and I really should try Armageddon first.
I would like to see Paradox and the modding community settling on one Hearts of Iron game, and get it fixed in every way (using patches and new releases) before the game's evolution races on to yet another enhanced version. The greatest shortfall has always been the AI. Reading about both AoD (now at Patch 6) and HoI3 (needs Semper Fi to play properly) proves that the basic problem is not getting better. How can it if future Hearts of Iron games are so radically enhanced? Is it not true that the more enhanced a game is, the greater is the challenge to code an AI that can deal properly with the increased burden of greater complexity?
Hearts of Iron is a truely remarkable game. Unfortunately, the development of further enhancements has only - in my opinion - frustrated the focus to play a really good game that is really bug free, balanced all things that were written about for years (naval bombers and much more), fixed some really silly errors, made the game progessively more playable (easier to play), and built up better internal awareness of the consequences of specific player choices. Once that is all achieved, then the game is ready to slowly take on greater enhancements, IMO anyway.