Bbaxley2: What are you specifically looking for here that is lacking in the LS3? Anyone's "best" is always a subjective rating.
I too don't put much weight on a sweeping generality about all the products of a company. Wc65mustang: Why not share with us the two ARC models you owned? Were any of these by any chance: SP-14, SP-15, LS1, LS2, LS3, LS15, LS16, LS22? Any of these models I would avoid due to their (in my view) analytical presentation.
I currently run with the Callisto-Sig/Io combination and this clearly excels over the LS5/PH2 and BAT 31SE/P10 that preceeded it, but I would not describe the Aesthetix gear as smoking the ARC or BAT. The Aesthetix jupiter series simply portrays 3-dimensionality like no other products I have yet heard.
Since I have not heard the Ref2 or Ref3 with or without the Ref Phono, I will keep my comments to the models I know. As many people here know, I have tauted the LS5 (the III being my favorite due to tonal coherency over the II) as a wonderful line stage - I owned the LS5 for 7+ years. I have yet to hear anything else that comes close in the $1800-2300 range. Great great bloom, dynamic contrasts but the typical "out in the room" ARC presentation.
The SP-10 has a killer phono stage? Oh yes, but very noisy. I owned this for 8 years before the LS5 and only then did I realize how terrible the line stage was in the SP-10. This product really only makes sense for the phono die hard. And even then, I would consider using its tape outputs to drive a more refined (read: modern) line stage. This into the LS5 might be awesome....but kinda pricey.
If I was to stay with the ARC line, I too would look for models that did not use the 6H30 russian supertube. I had these in the BAT 31SE which I liked a lot, but there was no opportunity to customize the sound as Albert points out. It is amazing how you can tune the tonality and dimensionality of your system by trying various Telefunken, Mullard, Siemens and now the EI tubes.
So my vote goes for the LS5 if you're on a "budget". If you can afford more, it sounds like Albert's recommendation would be the next step or maybe the LS25 MK I as a third option as it too does not use the 6H30.
John