What I'd like to see in the near future is mostly:
1. 1-turn units could stay the same (maybe orcs/elves terrain bonus reduced to 5, pikemen's to 10), 2-turn units' cost a bit reduced (except yeti)
2. critical 100% (or 90%) for medusa
3. a 3rd hit for Sandworm/Griffin/Elemental would be imo acceptable. Griffins wouldn't become so strong, they could maybe become worth keeping or buying. Their price (above all Sandworm) should be kept high (less for elemental). They would become fearsome, but I don't think they would unbalance the game. Maybe we would see Griffins and elementals from time to time. Sandworm strength could be brought to 30 with 3HP
4. a rework for spiders (I'd reduce their natural strength, give them 16 moves, and some special abilities like swarm/critical), to make them reasonably powerful (more than minotaurs) and with a cost around 800, to make them the strongest 2 turn units after wizards. My proposal is:
Spider: 15+15(in city), critical 15-20%, move 16, cost 800
Minotaur: 25+10(in city), move 14 (or 12), cost 550
5. raising the cost for dragon/devil/grand archon ONLY if their presence in neutrals is eliminated, otherwise the advantage for finding them is too big.
6. unicorns in 3 turns, devil/grand archon in 5
7. lower cost for demon (it seems to me any other change would make him too powerful)