----------
How about asymmetric spawns, towers, terrain? And how worthwhile/balanced are spawn upgrades in competition to hero building?
----------
The reason to introduce asymmetry in an lpg is that you're confident that the advantages/disadvantages it creates will provoke action, as team try to capitalise on their advantages and exploit the enemy disadvantages.
In Dota2, certain heroes are considered better on Radiant/Dire, and Roshan is easier to take as Dire. In TI4, most teams rushed to the Radiant jungle at the start of the game, to place wards there or try get a kill. In a symmetric game, there would be no reason for teams to converge at a place and fight that early (without some other mechanic). So it can have benefits, though you sacrifice the cleanliness of perfect symmetry. That said, even League gets complaints that one team wins more because of the camera angle!
I have yet to come across spawn upgrades that I like. Collectively, they're either:
A boost to your troop's power that causes you to passively push lanes, smothering your opponents unless they also spend money on upgrades. No well-versed opponent will ignore upgrades, so in effect they are a very temporary advantage, for a few waves at most.
A game of rock-paper-scissors. Again, your advantage in playing rock only lasts until your opponent notices and plays paper. Temporary advantage for long-term disadvantage.
I don't find either of those satisfying mechanics to win with, or play against. They punish new players who don't know the system, and demand time/gold from players who have better things to be doing (like: having fun).
EotA has a lot of spawn upgrades. Team assets require a separate team resource so no individual has to foot the bill, which I like. But fundamentally, it's rock-paper-scissors for a temporary advantage, which lasts longer if your opponents are busy, don't know the system, or resource-starved. I think that outcome could probably be implemented in a cleaner way with less disadvantages.