From my experience getting 6 characters 7 starred from it id say low definetly gives more shard drops while high definetly gives more cantina shop points and rewards, but shards are more important right?
I did a cost/benefit analysis for the Cantina to check this out. There was not much of a difference, but in general, you get more credits per energy spent on the higher cost nodes. If you are trying to farm from both low and high energy nodes then an even split between the 2 is a good compromise. This was based primarily on the goal of acquiring 400 credits to purchase shards in the Cantina shop. Of course farming the low energy nodes will get you more chances at a shard drop, but will generally cost you more energy overall.
Replies
8 10 | credits energy
0 24 | 408 240
1 23 | 404 238
2 23 | 417 246
3 22 | 413 244
4 21 | 409 242
5 20 | 405 240
6 19 | 401 238
7 19 | 414 246
8 18 | 410 244
9 17 | 406 242
10 16 | 402 240
11 16 | 415 248
12 15 | 411 246
13 14 | 407 244
14 13 | 403 242
15 13 | 416 250
16 12 | 412 248
17 11 | 408 246
18 10 | 404 244
19 10 | 417 252
20 9 | 413 250
21 8 | 409 248
22 7 | 405 246
23 6 | 401 244
24 6 | 414 252
25 5 | 410 250
26 4 | 406 248
27 3 | 402 246
28 3 | 415 254
29 2 | 411 252
30 1 | 407 250
31 0 | 403 248