>>96321741
Funny enough, I feel the exact opposite. Low and high tiers are the fun ones, while mid tier is pretty boring.
At low tiers, you feel like normal people and have to get creative to succeed. Smart tactics and social interactions matter even for winning encounters. Here, though, you're better off playing something more gritty/lethal like OSR, WHFRP, or GURPS than 5e D&D.
At high tiers, you matter. You're a power player and you can swing your dick around if you want. The big issue is that the players have to be proactive and actually go out to do things, and the DM has to be willing to work with players rather than write a novel. But if you do that, you should feel like movers and shakers with significant agency.
At mid tiers, it's just kind of mediocre. You don't have the narrative agency of a high-tier character, but you don't have the stakes of a low-tier character either. At this point, progression feels like you're just filling out a build so you can get to the fun, high-tier gameplay.