Ballcock vs Float

[Flapper]

It seems that everyone replaces their ballcock valves with float cup valves, but why? Are float cup valves more reliable? Or are they quieter? Or are they just more convenient because of their form factor? I would think ballcock valves are more reliable because they are simpler and they have all that leverage from the float sealing the water back.
What are the pros and cons of the two types?

 

[Jadnashua]

They cost less, are easier to adjust, the floats don't leak, you can replace the wear seal in about a minute with no tools. They also (at least the vast majority of them) include anti-siphon valves that old ballcocks rarely had, and that's now required. Many of them refill faster since the water comes on full sooner during the flush, and stay near full volume until they turn off. Most of them have a soft close, some don't and those could be annoying if you have water hammer from loose pipes.

 

[Sponsor]

 

[hj]

The "float valves" have a fast shut off. The ballcocks taper off and the final flow before stopping creates a high velocity that cuts grooves into the seats and then you have a constant leak.