Have both, a JD9520 (only comes with the power shift), and a 9120 with power shift and pto. If you can swing it, go for the xx20 series, as the power shift is much better. Also if your doing tillage work, you will find the auto-shift will save you fuel and time, while getting more work done.

We have the 9120 on the metric equivalents of an 18.4 tire, as we use it to pull the planter. The 9520 is on the metric equivalents of a 20.8, but we run triples on it.

One other thought, if you have plans of a lot of heavy tillage, while your looking, I'd also look at what the price difference would be to jump to a 9220. The 9220 would give you the larger engine.