No matter where you go in the outdoors or how long you stay, hydration is something you really can't live without. There are many ways people like to hydrate themselves and each method has its pros and cons. Here is a list of the most common methods used for hydration:
The hard water bottle or "Nalgene" system: This is a pretty tried and true system which is used by most people to carry water. The upsides are that it is a easy to fill and pour container, and it is very durable, meaning it won't break and soak your pack. The downside to this system is that your water is not available on the move and if you use the water bottle holders on the side of the pack, there is a high risk that the water bottle might pop out in the hustle of outdoor activity.
The soft water bottle system: This is a relatively new system that was started by the "No disposable water bottles" campaign. It consists of a spout being connected to a thick plastic bag. The upsides to this system is that the bottle itself is very light and packs away to almost nothing if it is empty. The downside is that these bottles are not as easy to fill (from natural sources) or pour, and their durability is lacking, leading to a higher chance of a leak.
The hydration pack or "water bladder" system: When these first came out they were used exclusively with small hydration packs for mountain bikers and lightweight hikers. However now even large expedition packs will be hydration compatible. The upsides to this system is that it allows you to drink while on the move and without taking your pack off, (a huge bonus with a huge pack). The ability to drink all the time also, on average, leads to an individual staying more hydrated, because the effort to take a drink is negligible. The downsides are that they are pretty close to impossible to pour, and the hose and bite valve can freeze in sub zero temps, rendering your hydration bladder pretty useless (this can be helped by purchasing a insulated drinking tube, but it isn't full-proof).
Given all these options, these is no real "best" option, but rather an option or combination of options that will be best for a certain activity. For instance if you are going on a winter camping trip, you will probably only want to take hard water bottles to avoid freezing. But if you are on an ultra light backpacking trip you may opt to only carry soft water bottles or some combination of 2 or all 3 depending on the situation and your specific hydration needs.