I was using Excel for my personal budget; however, once I switch to using all Macs, I switched to using numbers. Main reason is that I can leave the spreadsheet open on my iMac and I can still edit it, while away from my house, on my iPhone and it will automatically update it on my iMac.
With excel, I can't do it (i tried but no go). It says that it is open already and I can't edit it.
Unless I get a job that requires me to have excel at home, I'm sticking with iWorks.