The galaxy tabs have good hardware but samsung is terrible at updating the OS. If you want data to go along with it, go with that or an HTC Flyer (View 4G). The nice thing about the Flyer is there is a stylus you can get that lets you write like a notepad for taking notes in class or what have you. If you want best bang for buck, go with Asus Transformer, its a bit cheaper but still very good, and it has the option of a dock that turns it into a laptop.
Steer clear of the sub-$400 tablets. They tend to have terrible screens, some don't include Google Apps such as the market, poor support, etc. Best to go with the big name brands like HTC or Samsung or Asus. I don't know anything about the Toshiba. The Motorola Xoom is pretty popular but has issues, and is the most expensive.
If I were to ever bother selling my Ipad I would replace it with an Asus Transformer, but that's just me.
http://www.nowinstock.net/computers/tablets/asus/
Other things to consider - tablets are generally either 7" or ~10". Some come as wireless only, some can have data plans with your cell phone provider. These two preferences make a big difference in what you will get, so figuring that out will help us recommend something.