Regarding proof-of-stake for example, I'll defer to this comment: https://news.ycombinator.com/item?id=25007874
For example, you can sell roughly 5 million USD worth of litecoin on the Bitfinex exchange until you push down the price by 0.5%, but for Bitcoin this figure is roughly 500 million USD (~100 times greater).
The greater the liquidity of a currency the less value is lost when exchanging back and forth between it and e.g. USD.
So you just demonstrated the problem that the OP was talking about.
I'm just someone who sees the failed promises made by Bitcoin (fast, cheap transactions) against the horrendous damage it is causing the environment.
There has to be a better way.
Fast and cheap transactions have been around since long before Bitcoin. Bitcoin's innovation was to make those possible without a trusted centralized intermediary. Therefore, decentralization and security are arguably the most important properties when evaluating cryptocurrencies. And Bitcoin is king on that front. Cryptocurrencies that promise faster, cheaper or "more energy efficient" transactions pretty much always have to compromise on that.
But as an end user, you probably wouldn't know that. That's why I'm frustrated with people who authoritatively claim things like "there are so many better crypto-currencies" while not disclosing that they're merely commenting from a "user experience" point of view.