I played NL2 6-max 100K hands and crushed it very easy.
It's simple to play. You can find a table with 5 loose players and there is a lot of such a tables as well.
After finishing 100K hands at NL2 I switched to NL5. I had a hard downswing at the beginning plus some mistakes from myself, but then the downswing has gone and I also improved my game.
At the NL5 a lot of loose players, but there is no more 5 whales at your table. Nevertheless there is still a lot of money you can take from those players.
And now I play NL10. It's not that hard, but a bit aggressively rather than NL5, so you need to adapt. And yes, there is still a lot of money.
I just finished my first 100K hands yesterday.