Too many variables for a simple answer? I don’t know.
Easiest APA, American IPA - throw more hops in! Water chemistry more easilty dealt with especially around 11-12 SRM.
Most difficult - Light lager - Helles - can’t hide anything in there. Faults stick out like a sore thumb.
I feel that dark beers-porter, stout-tend to mask off flavors, so to me the dark beers are easy. The APA’s and IPA aren’t bad either.
I’ll second that emotion. Hops will mask a lot of off-flavors as long as there are enough of 'em! 
I would think that any of the lighter lagers would be difficult, although I haven’t brewed many of them. I would also think that an Eisbock would have to be up there, since the freezing process will magnify any problems with the beer.
Agreed.
+1
Making good Lagers is harder than making good ales.
evidently i have the midas touch, i’ve never had a bad lager, but our water is perfect for this style of beer and my fermentations have almost always started within 12 hours
+1
I only brew ales, so from my perspective a cream ale is the hardest. The easiest I think is an amber. My reasing is that, while I agree a porter or stout can mask off flavors, darker beers can easily be overdone with too much acrid bitterness. Use a couple to many ounces of RB or BP and you have made one undrinkable beer. An amber on the other hand can take a healthy dose of hops or caramel malts and still be pleasant, while masking off flavors.
When this topic comes up, why does no one mention Geuze as the hardest to brew? You essentially would have to have a fantastic sour program to come close to this style… And 3 years is the minimum time!
Probably because so few brewers have actually made a Gueuze that no one even thinks of it.
I agree that APA/IPA is probably the easiest style to make a good example of, but I don’t necessarily agree that dark styles like porter or stout are just as easy. It may be easier to make a decent porter because the dark grains do mask fermentation flaws to some extent, but a good one is a bit more elusive. Getting the right balance where you get a roast this isn’t too soft, but also isn’t acrid can be a challenge. I find that water chemistry is just as important with dark beers as it is with really pale ones.
I make gueuze. It’s not that hard. Brew, transfer for aging, make sure airlock is full, wait, repeat, repeat, blend, bottle.
Light lagers are inherently hard.
But am I the only one who thinks that APA/IPA is actually hard? In my area, it seems like if you can brew a passable IPA or APA, you’ll be a shoo in for a gold medal. Almost makes me want to brew one!
Bigger and bolder the flavors in the style the easier it is to hide minor errors. Highly hopped beers also inherently avoid infections, which makes them almost impossible to screw up without trying.
Gueuze is not hard, especially with the sour blends you can buy from WY/WL/ECY. Time is doing all your hard work. All you’re really doing is making a simple wheat beer and letting it sit. There’s definitely a different skill when you’re talking about blending but blending is only challenging if you are trying to build a particular flavor profile. If you’re just blending the beers you have then there’s no skill involved. You’re just racking beers together. However, if you are trying to put together a particular flavor profile then it can be quite challenging, especially when you have a small number of beers available to blend.
I guess it’s sort of like doing a home improvement job: If you have the right tools, you can brew anything. If I had precision temperature control, I could brew lagers, I wasn’t able to brew a good dark beer until I figured my brewing water out… and Geuze requires an incredible amount of time and knowledge.
I’d say Pumpkin and spice beers are the most difficult to get right. Most of the time they are awful and over spiced
+1 to spiced beers in general. But Pumpkin is hard.
Personally, I struggle to make a nice simple Belgian blonde.
I’ve generally been pleased with the lagers I’ve brewed but I don’t try too often. Especially not light lagers, as they’re just not my thing.
But I simply can’t get to a Belgian blonde that I really enjoy. My last attempt was the best so far, but they’re falling short of what I want. These are not infected nor do they have off flavors but they’re just not what they should be, if you follow what I’m saying. They’re lacking. Perhaps I am like Sisyphus as I shall keep trying.
Easiest? I think saisons are pretty easy. As long as you don’t use 3724.
Light lager is difficult. I’ve yet to brew a good helles, but I think my fault was using Rahr pils. Yuck. Using Best Malz now. IPA is easy to make, but getting the flavor I want is a bit more difficult.
I’m also trying to get a good oatmeal stout going too, but I’m having some trouble getting the right amount of roast flavor. It’s coming up too chocolately, which isn’t working for me.
Same here!! I thought I was the only one!
I find WLP565 much easier to use than WY3724 with approximately the same flavor profile.
If you hit upon the magic formula, please let me know. Good to know I’m not the only one, too.
As for saisons, I’ve been happy enough with 3711. Never have used a White Labs vial. Someday, perhaps.