Driverless tractors may allow for bigger, heavier machines which would be better yet. The bigger the better because soil compaction goes up at a sub-linear rate to weight. While the soil compaction is worse for a heavier tractor where it touches the soil, the heavier tractor can handle a wider pass which means it overall doing much less damage vs a smaller tractor that would need to do several passes touching more soil to get the same work done. This is also why tracks are often worse than tires - even though tires compact the ground more where they touch the soil, the track touches more soil in a turn and thus does more damage in a turn than you save in the row!

Of course different soils are different. You need to discuss the particulars of an individual field before you can make a judgement on what is best. But overall bigger is better.