Reddit mentions of Paper Mate PhD Mechanical Pencil, Retractable, 0.50 mm, Black Barrel (67004)

The Paper Mate PhD is a good one. So is the Pentel Twist-Erase III, available in 0.5, 0.7, and 0.9mm leads.

I use the Ph.D Mechanical Pencil. It's huge but it has an awesome retractable eraser (the best I've used) and the grip is very comfortable.

edit: Was it the Pentel Icy?

Alright, I'm a bit of a hardcore nerd for this kind of thing.

I use a PHD Black Mechanical Pencil

I have very large hands and these things have a very nice weight and grip to them. I've had mine for about 2 years, and the only reason I replaced the previous one was because it was run over by a car. These things last.

As for erasers, I've preferred the Staedtler Erasers

It has a very nice consistency, removed anything left by the PHD, and never streaks. I would recommend using packaging tape to enforce the paper bit surrounding it, as it tends to fray, and it's useful to have as it keeps the eraser itself clean.

Since I don't use a sharpener, I'll instead delve into my favorite notebook, the Notebook One by Miquelrius. These things will last. They have a super durable outside cover, which will never split off like other notebooks. As an engineer, I like the graph paper variant, as it makes drawing circuits easier. The paper itself is a dream to write on, and is ever so slightly thicker, which just brings that quality to writing on it. They also come in 3 or 5 subject color coded variants, but I prefer the single subject versions.

Bonus round: Loose-Leaf Paper

National Brand 42-182

It's a bit tougher to get, and I don't know why. It's a white version of the green engineering paper that you see around university. It's much, much smoother to write on, and much more durable. It comes in 5x5 one inch grids with the borders thickened, which is a nice touch. I never use the back, as it's too dark, but these engineering pads are a dream.