depending on the budget and nature of your shoots,
- hollywood microdolly, reasonable price, quick set up, disadvantage is u cant use on uneven ground,
- hong kong dolly, pretty expensive, can use on dirt track if you have a good Grip set it up for you, disadvantage damn bulky, takes awhile to set up
- sliders, pretty cheap, easy set up, no ground consideration, disadvantage can't track very long distance