Let's say you want to obtain an ilvl 200, epic quality set of cloth robes. Via Wowhead, here are your options:
1. Obtain exalted reputation with the Kirin Tor. (Also gets you access to other rep rewards, and likely some combination of cash or dungeon drops depending on how you get there.)
2. Craft, or have crafted for you, one of the three Tailoring BOE robes (costs you a lot of money, but can be done immediately - earning said money probably netted you other stuff like rep, dungeon drops, etc).
3. Join an arena PVP team, earn some points, and obtain at least a 1675 rating in order to be allowed to spend them on the robe. (No other fringe benefits, beyond the fact that you now have a 1675 rated arena team.)
4. Kill one of two bosses in the 10-man Naxx raid. (You'll pick up a decent chunk of heroic badges in even a single run, and probably would get a shot at other loot.)
5. Spend 80 heroic badges. (Obviously, you earned these doing some form of dungeon content.)
6. Zerg down 10-man Archavon, which shouldn't take more than 15 minutes, and be friends with the Random Number Generator.
This afternoon, I came within the flip of a coin of the last option (actually the [Heroes' Frostfire Leggings], but I went with robes for this example because there more options for obtaining them), only to lose the roll to the other mage in the group. There's always more loot, so I'm sure I'll have more chances down the road.
The thing that does get to me a bit, though, is how easy getting a drop like that is compared to the solo options. Sure, Archavon is a reward for winning Wintergrasp, and you can only do the raid once a week. That said, I've been working on Kirin Tor rep for literally weeks. I'm doing Heroic dungeons whenever I get the chance. And yet, I'm one lucky roll away from cutting to the front of the line and wondering why I bothered with all the effort in between.
In another example, my Stone Keeper Shards count went over 100 today. I've been getting the majority of my shards via Wintergrasp daily quests, which also award a hefty chunk of honor (I'm wearing the PVP neck and ring rewards now) and Wintergrasp marks of honor (due to be good for something next patch). So typically I'm netting 6-7 shards per day. Well, that total is nothing compared to what you get in a heroic dungeon with the Wintergrasp buff up - 4 shards per boss, with some bosses that are very quick kills. For that matter, a single daily heroic dungeon run will net you at least five badges, and the PVE badge heirloom items cost only 40 badges, compared to 200 keeper shards for items that have PVP stats (which are probably going to be less desirable for leveling your alts).
Is the solo endgame worth it?
People complain frequently about how WoW is "dumbing down" to be accessible to "casuals" (I try to avoid using that word on this blog because it has no agreed-upon meaning within the community, but I suspect people can guess in this context), but make no mistake that the game's best rewards still come from group PVE content. If you have a 2 hour window and a choice between doing a heroic dungeon or running daily quests, it's an absolute no brainer - the heroic nets you 3-7 heroic badges, 9-15 Stone Keeper Shards if your side owns Wintergrasp, a massive pile of reputation, and whatever loot drops during the actual dungeon run.
Of course, one big difference is that the dailies are available whenever, on whatever schedule, while you're going to need to find a group if you want to do heroics. Still, if you find yourself faithfully logging in every day to spend 2 hours on daily quests and then see that progress dwarfed by what you can get in a single afternoon with a skilled group, it's enough to make you question why you spent all the effort on all the other stuff.
(In case anyone raises the effort argument, bear in mind that I'm talking about 5-man content, which you can often 1-shot with a group that has never seen it before, rather than raid content that requires weeks of farming and wiping to learn and complete.)
Ironically, I probably wouldn't even be raising this point if I NEVER did group content. Doing group content SOMETIMES is just enough to notice how much faster I obtain stuff than I do solo. Obviously, I still think it's worthwhile for the moment while the various rewards are streaming in fast and furious from all the reps and tokens I'm obtaining on a daily basis. Once I wrap up with most of the reps, though, it will be harder to justify spending the time online on days when I don't expect to find a group.