The single hook vs. double hook trigger question pops up quite frequently. The double hook was the original design. The original AK had a sheet metal receiver that was replaced with a milled receiver early in its operational life. The double hook milled set soldiered on till the AKM hit the operational level. One of the changes the AKM brought was a rate of fire reducer. The rate reducer was fitted to firing mechanism on the right side of the FCG. This required the right side hook be removed to fit the reducer. Now all the triggers were single hook.
As to which one is better. I can not tell or feel the difference in a standard double hook vs. single hook set up. The main thing I recommend is to look at your receiver trigger window and see how it is slotted. If it has one slot, go with a single hook design. If it has two slots you have the choice to go single or double hook.
I hope this helps.