Unfortunately, this is exactly what indicates a balance issue. If a majority of people think that one method of generating power is so much more efficient, cheaper, easier to set up, more sustainable to the point they won't consider using anything else, that power source needs to be brought back into balance with others. In an ideal world (read: practically impossible), energy sources would be divided into tiers. In every individual tier there should be balance - choosing a power source from one tier should only be a matter of personal preference, not of one being significantly more powerful than all others. Advancement through tiers should have a meaning, a tier 1 power source should not be powerful enough to last you through the whole game. As it is right now, you can very well use lava power from your first generator to running massfabs and industrial machines.
Vanilla IC advanced solars have the same problem: there is little reason to build anything else as they were cheap, efficient, and didn't require any additional infrastructure to run. GregTech balances them slightly - the cost becomes an issue (you need some advanced machinery to get them), and they are divided into tiers. A tier 1 solar will not be enough to run your whole base - there is an incentive to upgrading. And upgrading requires additional resources and processing, not just building more of the same machine (packed into a single block or not).
I don't think anyone really argues about lava generators in the overworld - lava is severely limited and any stationary power plant will only last for a short time. Therefore my proposed solution is to change worldgen so that the Nether spawns a different kind of lava - call it "superheated lava", which can not be pumped or put in buckets/cells. This keeps lava as a viable early-to-mid-game power source, and keeps the crucible->geothermal BC->IC conversion, but stops the practically infinite source of Nether lava power.