Most investors, including Fool contributor Evan Niu, are stacking up Apple's (AAPL 0.52%) new iPad Mini against the two leading 7-inch tablet competitors -- Amazon.com's (AMZN -1.65%) Kindle Fire HD and Google's (GOOGL -1.97%) Nexus 7, both of which start at $199. These two tablets certainly may stand to lose some sales to the iPad Mini, but Sterne Agee analyst Shaw Wu believes Microsoft (MSFT -2.45%) Windows 8 devices may be the main rivals. Wu maintains that since the Kindle Fire HD and Nexus 7 are much cheaper, they're in a different device category, while the iPad Mini's pricing puts it right up against Windows 8 PCs and tablets.