I dont use both and dont own both either (a decision i regret a little bit :S).
I like to use Dash/Litecoin for daily transactions and Ether if i have to.
I cant recall where i heared/read about this. The idea was the institutions / corporations (with huge interests) behind BTC core want to take/create a future position as a bank (the very thing we try to escape) with offchains/sidechains.
If i recall, I'll leave you a source for sure!
For quick cheap transactions, outside the Steem/Bitshares realm, I use Dogecoin mainly.
Really would like the info on the offchains and sidechains part. And I know that with Lightning has some people worried in that manor too. At least I want to dig deeper into that matter. What I do know is that there is a mud throwing contest between BTC and BCH fundamentalists. But that is the two dogs fighting over a bone thing. Could be good for other cryptos as they might get away with it. ;-)
If you recall it, let me know!