The reason the early Church used the LXX so much was not necessarily because it was superior to the Hebrew texts but simply because more often than not, that was all they had and for many, it may have been all they had ever known. The LXX was written in the first or second century BC. Unfortunately, the oldest MSS of the Hebrew text that we have dates from about the same time so we do not have anything earlier to compare it with. If you prefer the LXX text, that is fine. I do not have a problem with that. Personally, I question the superiority of any translation over the original language text.
Also, LXX is from the 3rd century BC, the earliest big portions of it preserved are from the 4th century AD.
MSS are from the 9th century AD, their origin is not known.
If you meant the Qumran texts from the 1st century AD, there are some portions close to MSS text, some close to LXX readings (even thoug in Hebrew). From this it is said that there existed several versions of the OT text in the first century. One was translated by the LXX, another version became later the basiss for the MSS.
The NT use of the LXX sacred the LXX line...