T3 has a round-up of iPad alternatives and lists the HTC Flyer, the Samsung Galaxy Tab 10.1, the LG Optimus Pad and the Acer Iconia Tab A500. (Also check the review.)
But don't forget the Notion Ink Adam, Motorola XOOM, Dell Streak and more from Toshiba, Asus and Archos.
Most of the Android tablets will be based on Android 3.0 aka Honeycomb and feature a powerful dual-core CPU. The iPad2 may even the playing field again come September, but until then Android rules the iPad in power. Usability and personal preferences remain, well personal. :)
Update: Sony Ericsson Play, XOO…