no one mentions cable head or diameter because we can assume that nearly all shift cables are the same type. there are a few very obscure exceptions to this, like bikes from the 1970s and earlier and maybe Campagnolo shifters. everything else uses a standard cable. regular stainless would be my choice, and replace the housing and ferrules while you're at it. most bike shops sell housing for $1–2 a foot and cables for $4–5 each, or you can buy a kit that comes with all you need to re-cable the shifting.