Hi, I think what inserts you use should be first of all guided by your drying conditions. If you have good access to outside sunshine and/or wind on a regular basis, the world is your oyster! If however you may struggle to dry them, or have to dry indoors or using a dryer then the faster drying fabrics are best - usually microfibre which is the fastest drying. BUT - thinner bamboo inserts or trifolds dry fast too, as do cotton flats and prefolds to a certain extent too as they are being opened up to dry. You won't know what's really going to work for you till your baby is here as he or she may be a power pee-er, or not so don't go to town on any one type for now, would be my recommendation but you can usually make whatever you have work maybe with some additions.
I have a power pee-er and mainly use a microfibe pocket nappy (internet no-name cheapy) boosted with a wee thin bamboo booster (from little lamb size ones I'm no longer using) under the microfibre. That way the micro absorbs fast, but the bamboo more completely. I was finding that if I doubled up the micro, it was too bulky and opened up the legs causing leaks but that was because they are just cheap naps. Bamboo can be really useful that way as it's absorbency is great without being too thick. I get on fine with these during the day, changing about every 2 - 3 hrs for pee and immediately for poos. I have a couple of better ones I got for going out for longer or long car journeys etc.
That was just what I was able to get a hold of though and make work, it depends on your budget too, there is no need to spend a fortune. I started off with small sized cotton prefolds, secured with a snappy and covered with a PUL wrap, as it meant I could get the fit I needed on the newborn spindly legs and you change so often at the first stage they were easy to wash and dry. The covers only needed changing with poop so about 3 sufficed with a couple of dozen prefolds and I used reuseable liners as well to keep his bum nice and dry. Prefolds or muslins can be a cheap one to begin with and the fold can be adapted to suit your baby and are also nice and natural but can take a beating in the wash. If you get them preloved they can be boiled before first use or even bleached if you are worried about any nasties (but rinse and rinse and rinse until you can't smell it at all if you go down that road - you don't want that in contact with your baby's new skin! A hot wash and good sunning should be enough.) I switched to the pockets when he had a bit of chub on his thighs and wasn't needing changed every 2 minutes, they are less bulky and easier to use (especially for husbands
) This site has good videos of folds for prefolds, it's really easy once you've done a couple - I tried them on a teddy before DS was born, my then 10 YO DD did too, then wanted to change nappies when he was born and she did, so it's not hard! https://www.thenappylady.co.uk/demovideoindividualnappies.html
Trial packs are a good way to get a feel for the style you prefer before committing to a whole stash as some shapes just don't fit some babies well, or at different stages of their growth, so it can be good to get a wee mixture.
Here is a good explanation of the different nappy styles and their pros and cons, it's a new Zealand website so not all brands may be available where you are but is a great intro to the different styles. It starts with prefolds, just read and then continue to the next page at the bottom to get the next style and so on: https://www.thenappylady.co.nz/nappystyles-prefold.html
Hemp is mega- absorbent but is a nightmare to dry, I've found and goes a bit cardboardy! I have awesomely good drying conditions for three quarters of the year but struggled with my one and only hemp nappy even in summer so gave up on it mainly. It is quite slow to absorb too so as they get older and pee more all at once it may not handle it well, I've found but it depends on the blend - it's often blended with other fabrics to make it a bit more flexible. Again you could always just get a couple if you wanted to try them without laying out a lot of money.
I would just get the nappies you can afford, with the standard microfibre inserts if that is what you are thinking and then see what you need to add later if you have any issues. Unless you would prefer to use only natural materials, in that case look into getting cotton, bamboo or hemp inserts, or a different style of nappy altogether. Small prefolds can be used inside pocket nappies too and can be picked up quite easily and cheaply second hand if you find you don't like microfibre for some reason.
Does it get really hot where you live? That is another factor to consider - the sweatiness factor! We get decent heat here in summer but I've not had many issues using microfibre pockets but if it gets seriously hot you may want to consider a natural fibre for summer and good breathable shells or covers. Especially for a boy - there is some studies suggesting the overheating from the plastics in disposables may be a factor in male infertility in later life so I'm not convinced microfibre nappies with thick PUL shells are that great in comparison but I think it would only be a factor in serious heat maybe, or with loads of clothing layers over, but they still are way more breathable than disposables.
If you get to the point of wanting to use them at night, I would recommend a two part nappy in a high absorbency fabric such as bamboo with a separate cover, with enough nappies to allow for an extra day's drying should you need it - 4 or so should suffice. I also use a reusable liner in my nappies made out of microfleece - you can just cut up an old clean microfleece baby blanket or similar and it does the job - it doesn't fray so you don't need to hem it. It helps keep the baby's bot dry and catches any poops to make it easy to flick them off into the toilet. Newborn poop doesn't need to be removed though if you are breastfeeding as it just dissolves in water - a pre-rinse gets rid of it and the sun will take out any yellow marks incredibly fast.
It will save you a fortune, go for it! My cheapies cost me $50 for 20 of them second hand (but they had only been used a handful of times, they were given as a gift and the lady didn't get into using cloth - be careful about buying second hand if they are well used as the elastics etc can give out and microfibre has a limited life really. You also don't know how they've been treated or mistreated but you can get good deals if you are careful about it and if they are cheap enough it may be worth the risk anyway. Always check the PUL inside all round the legs for wee cracks, the elastic for stretch and inserts for smells - either chemical or ammonia.) they are still going strong 18 months of constant use later. I have added the boosters and bought night nappies and the odd other ones too to top up my stash but overall I'd say I can't have spent more than $100 - $150 on nappies for all this time - I would have spent nearly $2,000 on disposables by now (they are way expensive here). I am proud to not be chucking all that plastic wrapped excrement into landfill too and it saves us on the waste disposal money (you pay for individual bags here). I didn't use cloth on my 1st DD either and had loads of poop explosions and leaks in disposables, It's happened once with poop in cloth (and that was the crunchy hemp one) and only a handful of times with the cloth and usually down to me not fitting the nappy correctly or forgetting to change it on time.
Sorry this turned into a book! Feel free to ask any questions you may have and I'll tell you what I know