Hey Tink,
it’s a little more complicated than an either or question. Coco and peat moss preform similar functions as mediums.
first off most people will tell you that pure moss/ coco Mixtures are is for people who want to set up a hydroponics system.
most people who grow with soil use a mixture or ratios of different substrates to create their medium. In general you are looking for 1 part sand / perlite/ coco/ moss for high drainage, 2 parts nutrient rich substance compost/ loam/ fertilized soil etc.
as an outdoor grower going straight in the ground, i use the sandy/rocky loam that is there and then mix peat, worm casting, chicken manure, cow manure, perlite, vermiculite, top soil, mulch, dry amendments then start the lasagna with a layer of mulch. never tried coco as i live in the bogs and dont see the use for myself. i would try coco if i lived closer to where it is produced
not sure if i would go coco coir myself, i think its probably a more demanding grow than other hydroponic or soil grow. it needs constant tending and monitoring, but that's something growers should be doing, anyway. i would think soil mix is more forgiving, than making any mistakes with coco coir.
peat moss - i occasionally use to mix with soil, but I have not much experience there, to be able to offer you anything benefitial. the canna terra professional soil mix contains lots of peat, which is what i'm using for current grow, so again reserve my judgement there until i use it more.
i'd almost recommend DWC instead, i think its an easier hydroponic method.