The Ottoneu Surplus Calculator or the Fangraphs Auction Calculator?
In my short bit of research, the Surplus Calc seems to be a bit more conservative, spreading the money around nicely while accounting for leaving some money on the table to use on adds in season while the Fangraphs Calc is a fair bit more aggressive, closer to a stars-and-scrubs approach without leaving money on the table.
I take both into account, but I tend to lean more towards the Surplus Calc.
Which one do you prefer? Are you using something else?