According to an estimate Bitmex has $470 million long while $260 million are short. On Bitfinex there’s $490 million long and $120 million short.
Binance is a very distant third as can be seen with just $31 million long and $20 million short.
Binance is the most bearish currently, while finex is very bullish with a 70%-30% split in total.
The above figures for Bitmex are estimated but Bitfinex reveals them openly as shown.
Longs there have reached all time high, much of it just in the past few days. Presumably because eth bullishness made bitcoiners margin.
For eth, there are $140 million long on Bitfinex and only circa $22 million short. Some $80 million long on Bitmex, with just $18 million long. No Binance.
From this it clearly appears eth is more bullish, not least because it has risen more than bitcoin recently, but it seems to be attracting less volume than bitcoin.
One reason might be that ethereans probably prefer Deribit as that allows trading on eth deposits instead of just bitcoin like on Bitmex.
In addition ethereum has decentralized margins, from DAI to plenty of other dapps in the defi space.
That is not counted above because it is still a very new area with stats probably in development, but it seems interesting eth is attracting 25% of bitcoin longs while its market cap is only 15% that of bitcoin.