It's hard to give a definitive answer to this question, as organic pads from brand A are not equal to organic pads from brand B (some brands even have multiple types of organic pad compounds), same goes for metallic pads.
German Mountainbike Magazin did an extensive laboratory braking force test a few years back: https://www.mountainbike-magazin.de/parts/22-bremsbelaege-im-test/#bildergalerie
The pads with the highest braking force in this test all are organic ones. This correlates with my own experience. But it doesn't mean all organic pads are better then all metallic pads, especially when you compare cheap organic with expensive metallic pads.
Generally organic pads offer more initial bite, while metallic pads are getting stronger as they heat up (same goes for organic pads, but the effect is much more pronounced in metallic pads). Also, metallic pads take longer to bed in. On the other hand, metallic pads are more "robust". They last longer and overheat/fade later then organic pads but are often noisier.
There is a third kind of pads, semi-metallic. They are an inbetween of organic and metallic pads.
Regardless of type, you need to bed in the pads correctly. If you get them to hot before they are bedded in, they may never reach full stopping power. Common practice is to repeatedly get up to ~30km/h and brake hard until nearly stopped. Each time you should feel the braking power increase. Repeat 10-20 times until you don't feel it getting better anymore.
As for discs: In my experience they don't make a noticeable difference in braking power. Don't use resin only discs, even when only using organic pads they wear out faster. Heavier discs with thicker material and less holes take longer to overheat and are less prone to warping and bending. Bigger discs can! give you more braking power and stay cooler, maybe to cool. Especially if you are a light rider, who doesn't break much, this can mean your brakes won't reach the optimal operating temperature and smaller, hotter discs could give you more power. You need to check with the bike/fork manufacturer what the maximum size is.