One question is whether you really need them removed. What are you doing with that piece of land that the stumps are a problem? If you want to mow, you can cut or grind them to ground level. If you're worried about them rotting over time then subsiding......I vote for leaving them to rot, then put topsoil over them. You can spend a week taking them out now, or spend about half a day putting dirt on them 2-3 times over the next ten years.
If it's a cosmetic problem, grind them to just below ground level and cover.
If you're going to plow, disc or do other things that genuinely need them gone, then yeah, big excavator. Ideally with a person to drive it - they'll do it in a quarter the time you will, so unless you particularly want to drive a big machine (hint, I would), it's probably cheaper to rent an operator with machine than to just rent the machine.
If it's a cosmetic problem, grind them to just below ground level and cover.
If you're going to plow, disc or do other things that genuinely need them gone, then yeah, big excavator. Ideally with a person to drive it - they'll do it in a quarter the time you will, so unless you particularly want to drive a big machine (hint, I would), it's probably cheaper to rent an operator with machine than to just rent the machine.