My advice is to use your own judgement and experience as a brewer. Personally, I prefer the Wyeast calculator
. Mainly because it is easier to figure out multiple steps that yield your target pitching rate. Plus I brew exclusively with Wyeast so it makes things simple. I've always disliked Mr. Malty's use of multiple vials or packs for building starters. I think a better approach would be to make a smaller starter and step it up rather than pitch 2 or 3 packs of yeast at $8.00 a pop. Once you make enough starters, you'll get a feel for what works best for your beer. Until then, just pick the calculator that you think is best and roll with it.