First you need to have a price you are willing to pay. That will narrow down your choices especially if you want the computerized robotics. Unless, of course, you're sitting on a gold mine--then just waltz on over to Gammill or APQS and tell them you want one with everything to go--LOL!
Make a list and put price at the top. Then decide which features you must have and which you would like to have. Then go try as many as you can get your hands on.