I just wanted to elaborate a bit about history of Torah as we know it. Here is my other article on the subject.
First of all, we only have surviving witnesses from the 2nd Temple era. We do not have a single scroll of Torah from before that.
Three witnesses have survived and are known: Masoretic Text, Samaritan Pentateuch (Samaritan Torah) and the Dead Sea Scrolls (Qumran Scrolls). While there are not many significant differences between all three, Samaritan Pentateuch is still the most important one since it is still being used by Samaritans in worship. Septuagint (LXX) is another good source, but it is a translation (Hebrew to Greek) and most people even read translation of the translation (Hebrew-Greek-English or other language). Very few people a fluent in Ancient Greek.
What is important to understand is that we can't trust only one of the witnesses. We can only trust all of them together. Some people do not understand that Samaritan Pentateuch (and Dead Sea Scrolls) are very important sources of the Torah and can't be dismissed lightly.
I do not trust sages of the Talmud for that very reason. First of all, there was already Samaritan Pentateuch with all its differences in the time of the sages. Secondly, sages who wrote Talmud were from generation of the Temple destruction and final/total exile of Hebrews from the Land of Canaan. So how can one trust sages interpretation of the Torah if they were ones responsible for exile? Talmud is surely a great historical source and a decent Written Torah commentary, but it is by no means divine or even correct/relevant in our time and with our current knowledge of the Torah.
So, as you can see, it is important to use all Written Torah witnesses together as they all provide valuable information about the original text.