There is no "best" machine. As CKcowl and Paperprincess said, what is best for you may not best for me. And I don't necessarily agree that the most expensive machine is the best. Most people who invest in a LA research for at least a year before making a decision. Even then I have seen many LA quilters switch brands after many years of LA quilting. For example Angela Walters had a very bare bones Gammel and she has now switched over to HQ. I've also seen many switch over to Innova.
You need to decide many things before jumping in. For example do you plan on doing this as a business or only for your own quilts. If only for yourself, there may not be much point in getting one of the big "industrial duty" machines. Are you planning on doing hand guided LA quilting or buying something that is computer driven? Do you want to do show quilts? Do you want a basic mechanical machine you can perhaps work on yourself or do you want something that is all electronics, and you have to go to your dealer if anything goes the least bit whacky on it like the new Bernina LA where you can't adjust your own timing, adjusting the tension is done on a computer touch screen and the stitch regulator doesn't run encoders on the rails but is an electronic sensor with a laser eye? It is a gorgeous machine but too many high tech things to go wrong IMHO. Believe me you want to be able to tweek now and then. Have you even tried LA quilting to know if you like it? How important is it to have a rack you can modify and put hydraulic lifts on so you can sit at the machine with a saddle stool instead of standing at it. What quality is the rack? Do you want to have to adjust the take up roller as you advance the quilt or have a dead bar so you don't have to adjust the take up roller? As the others have said, you need to make a list of your wants and don't cares, set a budget and then go to a few major shows and try out as many machines as you can. And remember, just because you buy a certain brand doesn't mean you will be able to quilt like the award winning quilters who own that particular brand.
I have an Innova and its the best!
for me