Hello
A comment in passing in another thread made me think. It seems that in 5e the "sweet spot" is level 5-10. Now is it *exactly* 5-10? (4-9? 5-9? etc etc) but let's not worry about the exact value. The thing that is remarkable about this is that the "sweet spot" for 2e and 3e were *also* level 5-10 (roughly speaking). I don't think that everyone would agree (it would be a miracle ha!) but there seems to be a general consensus.
Why is that?
Low levels move by quickly in any edition of D&D, and doubly so in 5e. Low levels are also relatively low on choices--especially in older editions, but even in 4e that's true. In 5e in particular, you aren't really a "full" member of your class until level 3 for most characters. Low levels are swingy, and I feel 5e is more similar to the TSR editions on that front than 3e or 4e (though I have seen death in 4e games at early levels too). Things are often really gritty, and it's hard to get the "heroic" feel early on...especially when you're just punching rats in the sewer or whatever because you'd be massacred by anything much tougher (and yes, even in 5e, just a couple orcs is a naaaaaasty threat for a low-level party).
The higher levels are difficult to reach--in any edition of D&D. They tend to receive less overt support than low/mid levels, something that's held true with pretty much every edition (IIRC, 5e doesn't yet have a
single official adventure meant for characters higher than...I want to say it's 15th level, but it might be 17th). Crucially, they also tend to receive
much less playtesting than low/mid levels: 3e suffered
terribly from designers assuming that testing up to about level 6 or 8 reflected the power curve for the rest of the game, and 4e
might have avoided the outcry against "feat taxes" if they'd tested Paragon and Epic more heavily. Finally, high levels have often meant a fundamental change in
tone for the game; in older editions, you were "expected" to shift to domain management or to even retire the character, well before reaching 20th level, and in newer editions, keeping up the threat escalation can result in..."drama fatigue" for lack of a better word (I've never felt that myself, but I hear rumblings often enough to think it's a thing, even if never named as such).
The middle levels--which vary from edition to edition--are desirable because they're a crossroads. The game has enough moving parts and challenges to be interesting, it retains the "expected" tone, it's generally not TOO unbalanced, characters are more likely to endure (perhaps by the skin of their teeth) and thus generate a longer and "richer" history, DMs are better-supported with setting material/monsters/premade adventures/etc., it generally takes a little longer to get from level to level...
It's a D&D "Goldilocks zone." Not too weak, not too powerful...just right. Not too quick, not too slow...just right. Not too gritty, not to "distant" (for lack of a better term for what happens when you switch to domain management rather than cleaning out dungeons yourself). Not too "mundane" (punching rats in the sewer), not too "gonzo" (sailing the Astral Sea to kill a dead god). That plus the breadth of official support makes it, IMO, practically guaranteed that "the mid-levels" will be the subjectively "best" parts of the game.
Edit:
If I had to rate my estimates of the "sweet spots" for the editions I've actually played (not counting B/X because I didn't even get a level up in that)...
3e: 1-6 or perhaps 1-8, but no higher
4e: The whole thing? Level 1/2 is still on the dangerous side, but everything I've heard suggests that it hits the "sweet spot" quickly and doesn't leave it. I have, in fairness, also heard that Epic can get bogged down if you aren't careful, so I guess at
bare minimum it'd be like 3-21 (which equates to 2-14 in those editions that go to 20).
5e: at very best, 3-14. Probably more like 5-12. 3 is when the game finally gives you all your
basic toys--you need a couple more levels to get to "juicy" stuff (2nd attack for melee types, 3rd level spells for full casters, 2nd level spells for half-casters, Font of Inspiration for Bards, Uncanny Dodge for Rogues)