Triggers: I've used VQ, PC and Kidd do-it-yourself kits, reworks by TT Shooter and full assemblies by VQ and Jard. For the DIY, the Kidd beats all the rest as well as the full VQ kit.
Barrels: Green Mt, ER Shaw,and Whistle Pig all have been used here. A Kidd and another Green Mt are awaiting the rest of their components for their respective builds. I really like the Whistle Pg for their performance, their finishes and their great customer service.
Optics: Nikon, Mueller and Burris. As a bare minimum it's Mueller. Bushnell and Simmons just aren't close to what they used to be and BSA...wouldn't take the gift of one of them again.
Personally, unless you've tried a number of choices, there's no reasonable "this is the best".