Depends how busy you are going to be and what you want to do with it….Excel has a limitation of some 65,000 rows of data and 255 columns per worksheet and the number of worksheets limited by your PC memory. You could feasibly have one worksheet per aircraft type or per country unless you went mad in the US. It makes things difficult to bring the lot together and produce a decent listing, log or for checking.
My current employer uses Access which most decent PCs will have as standard and would enable you to do everything you need in one table and its fairly intuitive to set up your own reports and forms using the wizards.

I started off using Foxpro as that was what I used in my previous job and that is even more capable of doing reports and checking but does need some basic knowledge of programs to get you going.

Of the ready populated databases available for the spotter, I concluded that Aerodata’s Quantum plus has the better quality and most aircraft.

Pay your money and take your pick. Make sure that whatever you choose doesn’t tie you in the house.