The thing that I don't like about a hydration bladder is that if it gets one tiny leak, then it is worthless. Nevermind the replacement expense. Assuming that the leak is on the bottom, you have to invert it to get the leak on the top in order to minimize the leakage damage.
The venerable Gatorade bottle works fine for me. On a long, hot day, I will carry two, one liter each, and those always fit into the side pockets on my pack. The plastic is a little heavier than a disposable water bottle, but they are more durable. I'm currently using bottles that are about ten years old, and I don't know if I will get more than 15 or 20 years out of them.
I led a trip one time with a guy who started with a hydration bladder in his pack. Then on Day One, it got a leak. From then on, half of our effort revolved around accommodating him with the bladder.