As stated above the traditional woven selvedge is often the cleanest edge, without edge thickening of the tuck selvedge made by the short sections of excess thread turned over and tucked back in before being cut off. But, depending on the mill and even the individual tartan run, traditional selvedge can suffer from variable tensions in the thread lines that can give that slightly wavy edge effect. Tuck in selvedge does not suffer that effect, but rather suffers the aforementioned edge thickening, and the visibility of the tuck in thread ends may be more noticeable depending on how skillfully the mill places the cut edge of the tucked threads into an existing color change line in the tartan, as well as how tightly they cut those ends to the rest of the tartan. In the samples I have seen Strathmore, Dalgleish, and House of Edgar seem most successful at getting good results from the standard selvedge, while Lochcarron seems to get the best results from the tuck in selvedge. HOE's Nevis and Many of Marton Mills tuck ins can have very visible excess thread lines. Some of the lighter weight woven selvedges seem to suffer more from the wavy effect than their heavyweight counterparts. But with either it can be a luck of the draw with whatever piece of fabric in whatever tartan you happen to get, regardless of which mill it comes from. IMHO of what I have seen Strathmore and Lochcarron seem to be the most consistently reliable of each type, but then I am not a kiltmaker and have not seen the large numbers of different tartans in different weights from each of the different mills. I have one Batley kilt in 13 oz as well as a piece of 16 oz tartan from them---the thirteen seems to be woven edge while the 16 is definitely a slightly ragged tuck in edge. There are not really a whole lot of other "smaller" mills out there--I can only think of one, and then not even by name (Islay mills possibly?)---it is the one that several years ago wove the loose tartan for the Braveheart movie---unless you start counting those making harris tweed type tartan cloth.