It is hard for me to understand that most of the surgeons would select an ALIF over a TLIF. Have you been consulting with only neurosurgeons?
When you indicate a “lateral fusion”, I assume you mean a posterolateral fusion. The difference is that a lateral fusion (DLIF or XLIF) is performed through the side of the body and will not work for L5-S1 as the iliac crest prevents access.
The posterolateral fusion is performed only from the back of the spine. Generally this fusion should always be included when the incision is from the back of the spine although I have seen some cases where for some unknown reasons, it was not done.
You want a solid fusion as the primary goal of this surgery. In my opinion, this means prepare all potential surfaces for fusion mass. This means the disc space and both posterolateral regions (called the transverse-alar interval).
The statement that “obtaining the largest fusion bed from ALIF will provide the most support and will not require second surgery. I am told the intervertebral fusion will not be nearly as strong with the smaller TLIF or PLIF cages” is blatantly wrong. The TLIF prepares the disc space just as well as the ALIF and fusion is improved by both instrumentation which stabilizes the spine and by the posterolateral fusion which allows for more surface area for fusion.
I have about a 99% fusion rate using the TLIF procedure and I doubt that the individuals you have talked to have that fusion rate.