So for a couple days after saying Immortals are useless, spending hours at excel, and get bashed here in the forums, I decided to actually TRY them, so I replaced 1 dragon for 2 immortals in a 32 card deck. (only 2 upgrades -- towers)
First I played for about 1 hour against AI lvl 3. There was not one game that immortals made any difference whatsoever. Either I won easily (95%), or I lost because of AI super drawing / rainbow decks with massive luck.
Then I played Top 50, something I never did with mono-aether before... and I must admit, it was a great failure. Not the immortals, the deck itself. I can't say for sure but it appeared to me that nearly 100% of top50 decks have a way chain-disable our shields OR chain-sabotage our quanta OR spam so much damage so fast that my deck without full upgrades pillars were too slow. Most top50 aether decks are not pure-aether (I fought many aether, but only 1 was "pure"), mostly are aether + conflag or steal, some using mark of fire, some using pillars.
Then I played against gods, and was fairly decent, better than last time, 20 fights, 3 wins, 1 card.
Back on the topic, I don't think it makes much difference if you choose an immortal over a dragon, the fact that weird mathematical numbers done in excel indicate marginal advantages of one card over the other is of little importance when you look at the big picture.
Out of topic now, I'm quite disappointed with Elements, I played top 50 decks I saw the power of upgraded cards and the power of other decks, and I don't have the time or patience to farm them, and I'm regretting that my 2 hard earned upgrades were put in aether pillars because right now all I want is to play other elements and start to build my rainbow deck, which require quantum towers