Assuming that you are putting a system together from scratch, you ought to tell us what speakers you intend to use, what your source(s) will be, and what type of sound you have liked or disliked in the past.
That said, I would suggest you call ARC and talk to Calvin. Even though some of the amps you are considering are out of production, you will get honest and knowledgeable advice. I can tell you that the VS115 is going to sound a bit more "authoritative" and extended at both frequency extremes than the VS110, but also a bit more solid-state like (or neutral). The VS110 goes for less than half the price of a used VS115. If you do get a VS110, invest $300 or so for an octet of SED6550s and 6N1P-EBs and bias it down from 65 to 55mv. I had the tech at ARC confirm this is the way to go.
That said, I would suggest you call ARC and talk to Calvin. Even though some of the amps you are considering are out of production, you will get honest and knowledgeable advice. I can tell you that the VS115 is going to sound a bit more "authoritative" and extended at both frequency extremes than the VS110, but also a bit more solid-state like (or neutral). The VS110 goes for less than half the price of a used VS115. If you do get a VS110, invest $300 or so for an octet of SED6550s and 6N1P-EBs and bias it down from 65 to 55mv. I had the tech at ARC confirm this is the way to go.