I haven't seen any threads tackling this and asked this yesterday on the DHT. I now have some official results:

TL;DR - (1) with bunnies encountered, ELT is substantially better

(2) Boss only, LGD is marginally better by .2 coins per energy whereas ELT gives 3 sunstones per energy higher than LGD

(3) depending on the actual encounter rate, it might be better to farm ELT instead

LGD:

40 EN

1,000 Sunstone - 25/EN

680 Coin - 17/EN

With Leaf Bunny (encounter rate??)

1,000 Sunstone - 50/EN

3,000 Coin - 92/EN

ELT:

25 EN

700 Sunstone - 28/EN

420 Coin - 16.8/EN

With Leaf Bunny (encounter rate??)

900 Sunstone - 64/EN

2,500 Coins - 116.8/EN

Some maths:

** THE ENCOUNTER RATE STATED HERE IS HYPOTHETICAL**

At 200 energy, we can run lgd 5 times and elt 8 times and gives us:

6400 coins with a 15.2% encounter rate on ELT

6400 coins with a 20% encounter rate on LGD

10900 coins with a 37.7% encounter rate on ELT

10900 coins with a 50% encounter rate on LGD

Disclaimer: I didn't count how many runs I've made on each difficulty and of that, how many times the bunnies were encountered

Edit: removed previous conclusion. At lower encounter rates, LGD only has to have a smaller increase in encounter rate for it to be better than ELT

https://m.imgur.com/gallery/hbgCv0j ELT on top, LGD bottom

550% Bonus (1 5* base, 1 7* friend unit, 2 xons, 2 aidens)

**Apologies for not using proper formatting, I'm only writing this on the phone and have no experience in reddit formatting.

Message me if you want the complete maths table and I can email it to you