Choose a machine that can print both PLA and ABS. A heated bed make things a lot easier. Think about the parts you want print. Size your printer to your needs. Ask about print times. A simple flipper bat on some well known printers can take up to 4-1/2 hours. Others can do it in 2 hours.
Take a look at Lultzbot for large size parts. SeeMecnc.com for Delta bots. You can save some $$$ and buy a 3D printer in kit form.
If you are thinking about Makerbot, read the fourms about their return policy/customer support.