Sizing dies:
I've used enough to have an opinion Lee, RCBS, and Forster Benchrest (not bushing type). Forster is my favorite, and I have no gripes with them.
Lee: I dislike the pin clamping system, has screwed up on me a few times over the years. Otherwise works great.
Lee Collet neck sizers: love love love these things.
RCBS: expander ball sucks, compounded by the fact that RCBS dies tend to size the neck smaller than needed, I get tired of having to muscle the upstroke on the press. Meh.
Seating:
RCBS, Forster, Lee, Hornady, and Frankford Arsenal Universal seating die.
Forster seater with the sleeve makes the straightest ammo says my run out gauge.
Frankford Arsenal, Lee, and the Hornady with the sliding neck bushing thing are all tied as a close second.
RCBS has been hit or miss for me, my 6.5 Creedmoor die could not load straight ammo for love or money. My 30-06 die dies. My 7mm-08 is bested by the Frankford Arsenal and Lee, you get the idea.
All of which is a long winded way of saying, I rate Forster the best FL and Seating dies. Lee is the best neck sizing, and 2nd place in my list for FL. Lee and Frankford Arsenal are tied for 2nd place in seating dies.
Have never used Redding, Lyman, etc. maybe I'm missing out?