In my experience BTC tends to have slightly faster acceptance rates, but ETH technically has higher network throughput. I believe however that with the huge numbers of ERC20 tokens being moved around that the Ethereum network is closer to reaching its maximum capacity most of the time, hence confirmations are sometimes slower. Overall, both these are under 20tps.
It's also about the number of transactions for the both coins. Ethereum is transacted in the largest number while bitcoin transaction are a fraction of it.
Ethereum is of course a better when it comes to fast transactions, transacting more than bitcoin per secoind. but the number of transactions are huge in Ethereum than in Bitcoin which leads to larger queuing period for Ethereum than bitcoin.
True, if you include ERC20 transactions I am fairly sure that ETH eclipses BTC, however you can't really claim that makes ETH better than BTC. After all, many would consider ERC20 transactions to be network spam, since the vast majority of these are simple trades, whilst almost all of BTC value exchange is purposeful.
Either way, both networks need an upgrade, Bitcoin is steadily gaining numbers with Lightning and Ethereum has the impending Caspar upgrade, personally I prefer the idea of sharding over lightning, but we'll see who wins.
