Vandersteen Quattros are nice with AR amps too. The Wood Quatrros are even nicer.
Green Mountain Audio speakers work well with ARCs too. That's what I use with my VSi60. My friend uses Thiels (3.7s?) with his ARC (VS60), and it's very similar to my setup. I think any of the so-called "time-aligned" speakers are good matches with ARC amps, although I don't know why this would be.