7 of one, and half-dozen of another. They both get the job done. I think it is a matter of how many batches at one time vs batches per year.
If cost is a factor, go with the cheapest option that can handle the number of bottles you use at one time.
Cons of the Bottle Tree:
Peg can break off
Peg goes inside your bottle (one more thing you have to make sure is sanitized)
Slightly slower putting bottles onto the tree vs into fastrack (and getting them off).
Cons of Fastrack
Doesn't handle champagne bottles well - ring to hold on cork may not fit through hole in fastrack
If you are going to stack, then make sure you load 4 identical bottles on the corners.
If you stack, it gets the outside of the bottles on the lower tier wet.
I've used both, and prefer fastrack. I also use one to drain/dry bottles after they are used.
If you box empty bottles, it has a nifty ability to box the bottles in one step - put an upside down box around the bottles and flip the entire bunch.
If you do more than one batch at a time, I would prefer to use Fastrack to handle 60 bottles at once vs bottle tree.
Also think about storage between uses.
BTW: If you cook, the 1/2 sheet pans are great for a drain pan for the fastrack. The fastrack drain pan is also nice for holding the blue drain collar for carboys.