הביאו להם יין אחר אינו מברך בורא פרי הגפן אבל מברך עליו הטוב והמטיב: הגה אע"ג שאין לו עוד מן הראשון (ב"י) ולאו דוקא הביאו להם מחדש אלא ה"ה אם היה להם מתחלה ב' יינות מברכין על השני הטוב והמטיב: הגה ודוקא שלא היו לפניו יחד כשבירך בורא פרי הגפן אבל אם היו ביחד אינו צריך לברך אלא בורא פרי הגפן כמו שיתב' סעיף ג' (ד"ע להשוות הטור עם מרדכי פ' הרואה) (ב"י):

If they brought them another wine, he does not recite borei pri hagafen but does recite HaTov veHaMeitiv over it. Rema: Even if he no longer has any of the first wine. (Beit Yosef) And it is not specifically when they brought a new wine — the same applies if they had two wines from the beginning, they recite HaTov veHaMeitiv over the second. Rema: This applies specifically when both wines were not before him together when he recited borei pri hagafen, but if they were both there together he need only recite borei pri hagafen, as will be explained in section 3. (D"E to reconcile the Tur with Mordechai, ch. HaRo'eh) (Beit Yosef)

One recites HaTov veHaMeitiv over any change of wine by default, even if he does not know that the second is superior to the first, as long as he does not know it is inferior. Rema: There is no distinction between both being new, or one new and one old. (Beit Yosef in the name of Tosafot, ch. HaRo'eh, Tur, and Terumat HaDeshen §34) And this applies even if he drank from it within thirty days. Some say that if one first drank red wine and they brought him white wine — even if it is of lower quality — he recites HaTov veHaMeitiv, since white wine is healthier for the body than red. (Mordechai, ch. Arvei Pesachim)

If they brought him poor wine and good wine together, he should immediately recite borei pri hagafen over the good wine and thereby exempt the poor wine — he should not first recite borei pri hagafen over the poor wine in order to then recite HaTov veHaMeitiv over it, for one should always bless over the primary and the more beloved item first.

One should only recite HaTov veHaMeitiv if there is someone else with him, as the blessing implies — good for him and benefiting his fellow — and the same applies if his wife and children are with him; but if he is alone, he should not recite it.

If many people are reclining at a meal, each one recites HaTov veHaMeitiv for himself, and one person should not recite it on behalf of all, since we are concerned that they may have the windpipe precede the esophagus when they answer Amen. Rema: But if they were reclining to drink without eating, one recites it on behalf of all. (See above, end of §174)

Wine from two barrels, both of the same type — if within forty days of the harvest it was placed in two separate vessels, they are considered two different types and one recites HaTov veHaMeitiv over it. If they were divided after forty days, one does not recite it, since it is all of one type.