I’ve owned an LS 26, and now have an ARC Ref 5se. The LS 26 was a disappointment. It had a beautiful midrange - I literally stopped in my tracks when I first fired it up and put on CSN, and I was out of the room in the doorway! But it was bass shy. That last low octave was mostly gone. A deal breaker for me, maybe not for you. I sold it quickly and got a SS Krell pre to go with Krell FSB 400cx. Plenty of beautiful bass, but I always missed that organic mid on the ARC. Now I have a Ref 5se mated to a Pass Labs X250.8 amp. Upstream it’s a Ref CD 8. The Ref 5se is amazing. It does it all, from top to bottom. From what I’ve read, the 5se was the start of new voicing for ARC. Before, ARC’s have had a wonderful, clear, natural mid (“lit from within”), but it’s often called “a little white”. Not bright or clinical at all, but a little dry. The 5se kept all the goodness and added a little warmth in the lower mid, which for my Wilson speakers is a good thing. The Ref 3 was a milestone in its day and people loved it. It’s said that the Ref 5 was not that much of an improvement. So IMO go with a Ref 3 if funds are limited, else save up for a 5se.
