I also tried a 50 games run vs AI4 this Sunday.
This was my deck:
Results:
50 Games
46 Wins
4 Losses
21 EMs
I guess the luck was on my side
I wouldnt expect 21 EMs (although sometimes I delayed the game end for 1-2 turns to try an EM). As its a control deck, 12,1 TTW.
Electrum rewards (including double spins): 2628, -80 (losses) = 2548, which is 50,96 / game.
Cards obtained is highly variable, but I was also lucky. I got 5 upgraded cards (Firefly, Ice Lance, Improved Fog, Chimera and Improved Steal), and 5 basic cards (Bonds, Quint, Flooding, Horned Frog and Trident). Surprising, because basic cards drop rate is expected to be higher. 6081 Electrum from cards.
Total: 8629/50 = 172,58 electrum / game.
Did you get 7 upgraded cards in 38 wins, Tiko? Really? Wow, Kev have tested 300 wins, and the drop rate was about 7,7%. Guy, you were lucky this weekend
Hmmm, anyway, with a high win rate (92%), high EM rate (42%), and a good upgraded card drop rate (10,9% per victory), it was less than 3x what I got vs AI3. And playing is more than 3x longer. Not only like double of turns, but you also need to think about targets for SoFo and Oty skills. So, I wouldnt really be sure about AI4 farming being more profitable than AI3 farming (which is also much less luck dependant).
Of course I agree that playing AI4 is much more fun. Before my 200 games vs AI3, I wasnt playing AI3 for probably several months. And I also like playing AI4, I play them a bit almost everyday. What its unknown, and we will probably disagree, is which one is best for farming electrum.
Probably, farming FGs is the best, but to make it efficient (even more using unupgraded decks, or 6 upgrades decks), you need skip a lot of fights. And I hate to do that, because I care about score and win rate. About AI3 vs AI4, I would probably go for AI3. As my sample shows, its possible to get 60 electrum per game once you have an upgraded, efficient EM grinder deck (with games lasting about 1 minute). Because of this, I recommend to upgrade AI3 farmer before FG farmer. After that, if you need you can have like 3000+ electrum per hour of grinding, 2 upgraded cards for any deck you want to create.
Conclusion: I wouldnt go for FGs unupgraded (of course, people are free to do this). To farm electrum, I would do AI3. To have fun, surely not AI3. AI4 is ok if you want a mix of electrum and fun (although I think its hard to have fun using that mono aether deck).
Edit: upgraded cards drop rate for AI4 can really suck. I wasnt taking notes, but after +40 games vs AI4, with a 36-4 record, just +1 upgraded card (Precognition).