You need to tell people what attributes/qualities/sonics you seek here. At this price, there will be compromises in many places. And what is missing with yoru current line stage? And why have you singled out these two models vs. others? "Better" for you could be quite different than that for someone else. I've done enough bashing on the ARC LS2B on this site already, but I have not heard the 3i so I can not comment on it specifically. But both companies have made some great line stages in the last 10 years as well. Please do a search on these two products to get a feel for what people have to say about each of these.
John
John