Should my next computer be a Mac or a PC?

My imac G5 died a few months ago and I have been using a borrowed PC, but can’t decide what to buy next. I loved many aspects of my Mac, especially iphoto, but it only lived for 4 years, and I had to have the logic board replaced twice in that time, so didn’t seem that reliable. I also found it frustrating at times with compatability with pc users, ie when I emailed them documents and they couldn’t open attachments, or when they amended documents and sent them back the format had changed. I also sell on ebay from time to time, and Turbo Lister is unavailable for Mac. I also found it difficult to burn dvds of my home video. However, my Mac was great in that it was virus free and Leopard seems very appealing with Time Machine etc. I also backed up a lot of my data to an external hard drive which was formatted for mac and am concerned about how I am going to retrieve my photos/video from it. What would your advice be?