You have probably come to the wrong site for information about the best plums to grow for brandy. I don’t know of any members here who even have much knowledge of cider varieties.
This list, from Plumhill Farm in the Northeast, Z5, won’t really answer your question but might provide some ideas of varieties to experiment with. Any variety rated high on flavor undoubtedly gets up the brix.
Maybe you should be as concerned with productivity as taste. In the Northeast there is a wide range of productivity between plum types.
European Plums on the left, J. hybrids on the right. Values are rated 1–5 with lowest quality being 1. First number is production, second taste and third hardiness (not an issue where you are because it is winter hardiness).
I spent a good deal of time editing this to make it more readable but the program of the forum won’t let me do it. The edit looks fine with E plums and J plums clearly separated but the result goes up the same.
E. plums J plums
1 Starks Blue 4 2 4 Shiro 5 2 4
2 Early Laxton 4 3 4 Ozark Premier 3 4 2
3 PP 6995 5 3 4 Comet de Kumetz 5 1 5
4 Mt Royal 5 2 5 Methley 5 3 4
5 Fellenburg 5 4 4 Toka 4 3 4
6 Long John 4 3 4 Kaga 4 3 4
7 Early Blue 5 2 5 Gracious 5 3 4
8 NY71 5 3 5 Surprise (may be Kaga) 4 3 4
9 Castleton 5 3 5 Alderman 4 4 3
10 General Hand Purple Heart 5 5 3
11 Early Transparent Gage Early Costello 4 4 3
12 Ersinger 5 4 5 kahinta 5 3 4
13 Pearl 2 Ptistin #5 4
14 Empress 5 5 5 Pembina 5 3 5
15 Alabaster 3 4 4 Pipestone 5 3 5
16 Cambridge Gage Red heart 1 3 2
17 Imperial Epinese (not?) Starks Delicious 4 3 4
18 Hungarian Red 3 3 4 Red Glow 3 2 4
19 Opal 5 4 4 Superior 4 4 5
20 Kirkes Blue 4 4 4 Marisopal
21 Peach Plum 3 3 4 Obil’naja 5 4 4
22 Jefferson (blue prune) 3 4 3 Rema 5 3 3
23 De Montford 4 4 4 Au Auburn 3 3 3
24 Schoolhouse 5 3 5 Rose Marie 4 5 3
25 Mirabelle De Metz 3 4 3 Formosa 3 5 2
26 Mirabelle de Nancy 2 4 2 Sumumo 4 4 4
27 American Mirabelle 4 5 5 Early Golden
28 Oullins Gage 5 4 4 Satsuma (not?)
29 Seneca 3 4 4 Wickson
30 Royal de Vilvoorde 3 5 3 Duarte
31 Queen Anne 3 2 2
32 Yakima