Well then, I would rather pick Ethereum than it. Sure it aint that stable but it will be easy to come back since the price is getting cheaper.
If we look at the most stable top tier altcoin, then it definitely is XRP, but still, it can't compete with the characteristics stablecoins offer. People may not like their centralized nature, but they're doing their job exceptionally well.
There is a decentralized stablecoin called Dai, which operates on Ethereum, but there is little adoption and therefore not a good option if you want to take advantage of arbitrage opportunities across multiple platforms.