This is what I use for most stuff
0.3 mm and 0.4 mm Pentel Pro-Use HB
0.5 mm, 0.7 mm, and 0.9 mm Pentel Ain HB
1.4 mm Faber-Castell (I think it's one of the best I've used)
2.0 mm Staedtler Lumograph HB
3.15 mm Lamy-the one that comes in the Scribble. I buy it in bulk packs.
0.7 mm Pilot Eno (can be delicate and is more breakable than any of the above)
These are all for the most part easy to erase, have a good balance of nice dark marks and good wear resistance (you don't need to constantly advance the lead), are strong and don't break easily, and are pretty economical. I've also used Uni Nano Dia (0.3 mm, 0.4 mm, and 0.5 mm)-seems more breakable than my Pentel, Uni Kuru-Toga 0.3 mm and 0.5 mm-I didn't really like the feel as much, Pilot Eno (0.3 mm, 0.4 mm, 0.5 mm, 0.7 mm, and 0.9 mm)-very creamy, but quite strong. Seems slightly more breakable than my Pentel Ain, Caran D'ache (2.0 mm and 3.0 mm)-More breakable than Staedtler Lumograph and Lamy 3.15 mm, Faber-Castell 0.7 mm-This lead is also ok, but nothing special, Schmidt 0.5 mm and 0.7 mm-Ok, but does not compare to the others, Zebra (0.5 mm and 0.7 mm)-relatively hard in comparison to other leads of comparable hardness. I didn't like the feel as much, Lamy 0.5 mm and 0.7 mm-Ok, but not great, and more breakable than the others, Rotring 0.35 mm, 0.5 mm, and 0.7 mm-ok-I have no problems with it, and Staedtler Mars Micro Carbon 0.5 mm-the lead was more breakable, but it was fine, and the above leads are the ones I've chosen for regular use. The Ain Stein is a bit more expensive, so I haven't had much of a chance to try it. I did try it short term, but I haven't written so much with it, so I don't have anything to say about it. I've also omitted any leads that I've written less than a page with.
I typically buy my leads in bulk packs, so I have loads and loads of most leads that I use regularly.