To convert a large number of files, it can be very helpful to set Google Drive to automatically convert any file that is added to it (if Google has a corresponding file type, such as Word to Docs or Excel to Sheets).
Why Google Slides Instead of PowerPoint?
Also, your slideshow is easily available to you from any computer, tablet or phone.
And for anyone that loves picking out fun, atypical fonts, having your slideshow "cloud-based" (which it would be in Google Slides), you won't have to worry about which fonts are or aren't installed on a computer when opening on different computers. Google's fonts will open anywhere, so there will never be any formatting issues!