IMO, the key is the tines and how they are shaped and what they are made from.
Tines should be as thick as possible. Preferably square in cross section, not D-shaped with thin edges. A good steel is important.
It is hard to tell much regarding these characteristics from an Amazon ad. I will admit the Spear & Jackson in the same link caught my eye. It had me at "Solid forged from a single piece of steel for great strength". The tines look right in one of the close-up photos. That isn't a brand we have over here, so I don't know their reputation.
I have one that is similarly constructed that is 30 years old. Wedding present. I think it was from Gardener's Supply, but the brand name has worn off.
Any garden fork can be bent or broken. If you routinely need to turn rocky or rooted ground, and find yourself needing to exert a lot of pressure on the fork, get a good long-handled mattock or pickaxe to go with the fork. Or a digging bar. I sometimes need to excavate small quartz boulders, so I have both a pickaxe and a digging bar.
