I've been travelling around NZ in a mobile home for the last 3 years with my wife and kids. To be "connected" as much as possible, we decided to be on different networks. I'm with Spark (on skinny), and my wife is on Vodafone (on KoganMobile). We also use an RBI modem on Vodafone (via Netspeed) in the mobile home, and Spark (on Skinny Wireless) in our home.
What I've noticed is that Vodafone on 4G generally has the lowest lag (ping). In good coverage, and during offpeak, it can be as low as 20ms, usually around 30ms. However Spark 4G lag has consistently been above 50ms in the same circumstances.
I thought that perhaps, this is because a lot of Spark's sites are ex-Telecom analogue sites that are radio-fed rather than fibre-fed, like a lot of Vodafone's sites are. But these results can are irrelevant of location - urban, rural, Auckland, Taupo, Waiouru, Bennydale, Opotiki, Te Kaha, Christchurch, Greymouth or Arthur's Pass (just to name a few). Also, what I found strange is that this lag is also present on the shared RCG sites. Just last week, I was in front of the Raurimu RCG site (which I believe is fibre-fed for all operators) and I was getting 21ms on Vodafone and 48ms on Spark.
Has anyone else noticed that? Does anyone "in-the-know" care to comment?