Both are pretty crooked.

Ethereum is an open ponzi scheme ran by wealthy investors and there's the Goldmansach's connection.  To see any ROI (compared with the risk involved) on it, unless you invest six figures or more, you have to wait for Ethereum to hit billions..   when there is no incentive for subsequent investors to come in.  Ethereum videos on YouTube only have hundreds of views (minus the odd video which gets thousands) and  obscure media articles.  There's nothing there to build an million user base like Bitcoin.

By the way - it took Java and C++ a good decade to work out all the bugs and to educate a generation of developers to program in that code.  Ethereum creating a new language I think is more of a liability than a plus.

Stellar is a fork of Ripple with it being "free", the free part is almost a joke since right now it is a 99.7% premine and Stellar-Stripe currently controls 94% of tradeable Stellar at the moment (they have 5 billion versus the 300 million they issued so far).  The "SS" (Stellar Stripe) can easily manipulate prices much like the Ripple.  This is obviously a capitalization scam like Aurora was before the air drop (which made the Aurora developer very rich) and it can be compared with Marine Coin and Solar Coin and even Ripple.

SS promises they plan on distributing the remainder of their 99.7% premine but Ripple made the same claim years ago and reigned on it.  SS right now is doing the same.  They claim they are sending people $10 worth of Stellar but are sending less or none at all (accompanied with a congratulations email).  As well I don't see how they can get millions of users anytime soon, so Stellar will be sitting on a 99% premine for years.