My partner and I use QuickBooks. Seems to work just fine. It's easy and quick. I agree with a lot of these guys on here but in the back of my mind, at the end of the year I like to see exactly where I invested my money into the plane. On top of that, I like to look back to the first year we bought the plane and total up what we spent current.....radios, brakes, oil filter modification, etc, along with the time flown and see exactly what the cost per hour really is over the years (you want to be in the right state of mind when you do this.......maybe over dinner and some drinks). Just remember, when you look at the numbers, no matter what they are, think about why you started flying in the first place and why you bought a plane. The numbers seem to melt away.