Low levels. I love 'em. My players love 'em. They actually start to get somewhat disconnected from their characters around levels 5-6, as the powers mount and the challenges grow less about utilizing your brains to prevent your feeble body from being flayed alive by uncountable horrible foes and more about calculating your strength, mustering it, and throwing it where it is needed to topple dangerous enemies that would have, at one time, seemed like certain death.
It's this white-knuckled grip on the dice that interests my players most. The additional resources of high levels actually seem to be a burden. I've had them remark on several occasions that they LOVE playing the low levels. They've done it enough; TPKs, loss of players, and other such nicities have caused party resets a-plenty. But the more I think about it, the more I wonder if it hasn't all been due to one primary secret driving urge—my players like playing low-level schmucks. Sure, there's the essential draw of taking a paper-thin douchebag and turning him into a god... but do my players get bored of their douchebags long before they reach divine status? It would seem, by all evidence, so.
This is one of the reasons I've always wanted to run WFRP2e, why I love the current (but incomplete) rules for Medieval Hack (now Feudal Anarchy), and why I have sought out Hârnworld over and over again only to be repulsed by its not-quite-early-medieval setting (with its guilds and high medieval nonsense and strange words that look like Baatorian break-teeth languages). We just love the thrill of low-level play, and it seems like we always will. I've only run a handful of games with characters beyond 6th level in my life, and it doesn't look as though that number is going to increase anytime soon.