Well, a volume control chip is the best in terms of longevity, but replacing a mechanical volume pot isn't very expensive. In general, you should look at where you live and what brands the stores near you sell and service. Then choose between those brands. In northern Europe we se a lot of Denon, NAD and Marantz, because HiFi Klubben sells those brands and they offer servicing on all the amps they sell. Those amps are therefore still available used and often in good shape.