Finding The Right Buddhist "Vehicle" / Sect For An Individual I know there are three vehicles in Buddhism: Therevada, Mahayana, and Vajrayana. It seems there are so many sects of buddhism. Each of these three vehicles has sub-sects, (Zen, Pureland). Do the majority of Buddhist study each in depth in order to choose which fits them best in order to study the sutras accordingly? I find comfort in reading small pieces of sutras from each sect, though I've always loved Vajrayana and Zen. Is there a large difference?

On a side note: is the eightfold path is acknowledged by all three sects?
Demographically the majority of Buddhists today (nearly 99%) are born in Asia into Buddhists families and would likely follow their family or local tradition. 

But assuming your question is regarding those of us who have converted to Buddhism in primarily non Buddhist countries, there may still be no consensus on what the majority of these Buddhist converts do to select a tradition or sect.

One important consideration is whether one wishes to practice with a local group. If so, it might be more practical to gather information on local Buddhist centers/monasteries/temples and visit each to see where one might comfortably fit in and have an opportunity to study and practice along with other like minded local people rather than spending time learning in depth about traditions which may not be represented locally. 

If one is more interested in studying and practicing alone or in online communities, the possibilities are far less limited and studying at least the basics of each of 3 major branches and the major sub sects within the major branches could give one enough information to see which branch really peaked ones interest to begin a more in depth study into a particular branch. This answer links information on the various canons used in different traditions.

Finding a teacher whom one really feels they can learn from, whether a present day teacher teaching locally, online, or through books/videos or a historical teacher teaching through their writings, can certainly influence an individual's choice of sect too. When teachings resonate, the energy to learn more grows.

Your question is interesting to me because it's the same thing I wondered when I first began learning about Buddhism. The information on the various schools seemed overwhelming. I started with a local group to make things easier for myself. Then spotted some interesting online resources which made me think beyond the local group. Then found the energy to begin to study the different branches in a basic way and eventually found the tradition that really resonates for me. But I think if I had just sat down and tried to read up on everything all at once, it wouldn't have made much sense. :)