When we refer to ATH or other price dynamics, we refer to Bitstamp, here, unless we are trying to point out something specific about some other exchange.

So, in that regard, our ATH for 2019 has so far only gotten to $5,846. 

We cannot be referring to other exchanges with other ATH BTC prices, merely because it makes us feel better because there is a higher number or a lower number or anything like that.  We gotta stick to our guns during good times or bad times or whatever, and use Bitstamp as our reference price, unless there is some kind of convincing longer term development that shows us that Bitstamp is either no longer reliable as an price indicator, or some better price indicator proves itself to be better (likely with passage of time, rather than short term claims of serving as a more reliable indicator).