Start here: design, not technique, is what you are actually paying for
Nearly everything that makes a hair transplant look obviously transplanted happens at the hairline, and nearly all of it is design rather than technique. A line placed too low for the patient's age. A line drawn as a clean symmetrical curve when real hairlines are ragged. Multi-hair grafts in the front row, producing tufts where single hairs belong. Grafts angled upright when hairline hair grows forward at an acute angle. None of these is a complication in the usual sense; they are decisions, made once, and they are visible for life.
This is why the identity of the person who designs and makes the hairline incisions matters more than any branded technique a clinic advertises. A surgeon with good design judgement produces a natural hairline with any reasonable extraction method; one without it produces an unnatural hairline with the most expensive technique available.
It is worth asking directly, at the consultation, who specifically draws the line on your forehead on the day of surgery, and whether that is the same person described in the clinic's marketing material. In some high-volume settings, the surgeon who consults with you is not the same person who later draws and cuts the hairline, and knowing this in advance, rather than discovering it on the day, lets you make an informed decision about whether that arrangement is acceptable to you.