I agree with Bifwynne's response.
SP9 MKII nice. SP 11 was impressive. SP 17 wasn't impressive to me, but I was considering upgrading from the SP 11 and the SP 17 was actually the entry level pre-amp that someone suggested I try. Wasn't close to the SP 11.
REF 3 was a substantial upgrade that presented the sound in a very nice way. The SP 11 with new tubes was actually close, but the REF 3 was better in such a way that it justified (interesting word) my upgrade.
The REF 5 was just not that much better than the REF 3 to justify an upgrade to me. However, the REF 5SE was really nice and when I can, I will obtain one. It was a very nice unit that was "that" much better than the REF 3. Don't get me wrong, the REF 3 to this day still is better than most pre-amps out there.
I have heard many of the other AR pre-amps you listed, however, I would like to caution those that have not done direct A/B comparisons, to be careful in their descriptions as you are going by memory and not actually physical A/B comparisons.
The best thing to do when considering a new component is to take it home and simply remove the existing component and replace it with new and listen back and forth to your favorite music and see/hear if the differences justify purchasing the new one.
Mistakes that people make.
1. Purchasing based on someone else's opinion and not your own.
2. Not taking the equipment home for a direct in-home demonstration and see/hear for yourself. Then after purchasing without in-home demo first, taking it home only to find disappointment.
3. Letting someone pressure you into purchasing, when something inside you is telling you to slow down.
4. Being in the amp of the month club and purchase based on peer pressure.
enjoy