So I was trading between a market in Ukraine (Liqui.io, now defunct) and one in Japan (Binance.com). My server was in the US in the mid-west on a cheap provider. I found it was the best to reach either side. The round-trip to each was about 100-120ms. It's quite high, but my tests showed me that going anywhere else would increase one side so the best is to have the same time on each side. I am sure there is a lot of optimization to be done to my bot, but it had a good balance of sales/buy and I would rarely lose money.