It depends on what you want to use it for.
If all you want to do is browse the internet or check email, get a used ipad without the cellphone inside. "wifi" will hook up to wireless network hotspots and you can get a fairly inexpensive "wireless broadband router" to hook up to your modem at home so you can use the wireless "wifi" at home for any tablet, laptop, etc. that has a wireless "wifi" network adaptor.
Pretty much any ipad version will work. So will pretty much any android tablet, but in my experience the ipads are easier to use and the quality is very high.
If you need a general purpose computer like a laptop that you can also use as a tablet, you want a "convertible" laptop/tablet. Lenovo has some, not sure what other manufacturers have something like that. A convertible laptop will cost a lot more than most tablets. If I was on a very slim budget and needed a tablet though, I'd get a used or refurbished ipad with just the wifi.
