In term of global sales, Android tablet could be more than iPad these days. In term of usage, iPad would be much more than all Android tablets [1]. Additionally, an iPad has 2-3x life span than Android tablet on average (I has used over a dozen tablets). I seriously don't like to see so many low-quality tablets thrown into market. You are much better of buying second hand iPad.

[1] http://www.cultofmac.com/233063/ipads-web-usage-share-hits-5...