Which brands of primers have the hardest cups in the different sizes?

That is a tough call and a difficult question. It can vary from lot to lot too! I "mostly" find Winchester to be the hardest. Remington to be the softest. Others fall in the middle. I don't have a "list" for you.
I "tend" to find a load to use the primers that I have?

Why do you ask?

Cheezywan

 

The hardest primers are plated. Not much difference between brands when comparing this way.

 

On the whole pistol primers have softer cups than rifle primers. Reason is pistol ammo usually runs less pressure and pistol/revolver hammers have lighter hammer falls than most rifles.

 

In my experience Remington 7 1/2 Benchrest small rifle primers have cups quite a bit "harder" or stronger than the 6 1/2 primer. These used to be called a "magnum" primer and were, I believe, designed for the .223 and above cartridge. In cases where the 6 1/2 primer will edge perforate from pressure, the 7 1/2 will function normally. The difference between these two is quite glaring and worth mentioning. I use the 7 1/2 primer in the 6mm PPC and .223.

CCI also sells #34 and #41 Military Rifle Primers which have a less sensitive priming compound and thicker cups to prevent slam fires in semi-automatic rifles. These are mil spec primers and probably should not be used for normal sporting rifles, but reserved for the M-1 Garand and AR-15 type rifles.

The Winchester 8 1/2 Large Rifle Magnum primer is reportedly the "hottest" primer on the market, more so even than the Federal 215 Magnum primer. It has a cup designed to handle magnum pressures.

I use the Federal 215 Magnum Match primer in the 7mm Remington Magnum and the .375 Epstein Magnum, it has a fairly hard cup.

Generally, primers are designed according to the range of cartridges and pressures they will be used in. Remember, that primers are handmade, the little parts are stamped out, but the priming compound and those little parts are assembled by hand! I would never have guessed it.

 

For revolvers that are tuned - thus resulting in soft hammer blows Federal gets the nod