Sized vs One-Size

So you have finally selected the system you would like use, now comes the next issue: sized vs one size.
Sized diapers are much like disposables with sizes based on the weight of your baby whereas one-size (OS) is just that. 1 diaper with adjustment from 7-35 lbs on average. 
I think both have advantages and disadvantages and I like one or the other in different styles and brands.
For example I much prefer sized prefolds and covers because they fit the best on my son. I also prefer sized Fuzzibuns and Charlie Bananas also because of a better fit around the legs. I tried OS prefolds and they were enormous on my son for the longest time and then they seemed really weird anyway I folded them.  With Fuzzibuns an Charlie Bananas I just hated mucking with the elastics to adjust it just right.
On the other hand I LOVE my OS bumGeniuses and Giggle Lifes.  They did not fir quite right until my little guy was about 9 lbs and had some bulk in the thigh but after that they are great!
A definite advantage of sized diapers is they fit so well at whatever weight your baby is.  OS says they go from 7lbs but if you have a thin baby you may not be able to use them until 10lbs.
OS is definitely the more economical as you only need to buy the one set instead of several but the sizing is only a guideline!  You may also end up with more wear and tear on them then on a sized collection.
If you are just starting out on the journey of cloth I would strongly advise you NOT to invest all your funds in one or the other.  Just like I would advise you not to settle on one system without trying it.If you are just starting your stash get a mix of all styles and sized and OS and see what works on your little one.  Each baby is different and while I love prefolds and covers on a newborn you may prefer fitteds.  You don't know what you like until you try.  If you can get your hands on a diaper trial that lets you experiment.  If you do have to buy everything like I did just sell or trade what you don't like for what you do like.