I use the ZP (Hong Kong/China/Macau) iPhone 11 Pro; one key feature of being a ZP version is that it has two physical SIM card slots, allowing me to use two cards today. I use one card strictly for Local Calls and emergency data if needed and being my personal phone number I've been using for about 6 years now. I use another prepaid card for data.
I've done the calculations, and it's safe to say that I use A LOT of data. Usually more than 15GB a month, wayyyyyy more than when I compare to my friends. Previously, using only one SIM would result in me paying for a 15GB Plan at $250 HKD (32 USD) a month, which I thought was quite ridiculous. Having cheapskate Singaporean genes, I've set off to find methods to cut costs. Eventually, I came across the method I use today; on the main SIM, I pay $50 HKD ($6.4 USD)/month for 5000 minutes of calls and 600MB of 4G data. On the prepaid, I pay $33 HKD ($4.2 USD)/month for 50GB of data. Even when I include my current prepaid card for my Cellular iPad Pro at 33 HKD ($4.2 USD)/month as well, I'm looking at savings of 134 HKD ($17 USD) monthly. It might not seem like much at first, but it accumulates over time; the thought of having to total $1000 HKD within four months on the old plan seems extreme.
One of the main complaints about my old phone (iPhone XR) was the size; I personally felt like it could be smaller. The iPhone 11 Pro is the smallest Dual-SIM supported phone, thus I went to try and buy one used. Luckily earlier this year, dad upgraded to a 12 Pro, which was handed down from mum, who got a 13 Pro. I'm a happy owner of the ZP iPhone 11 Pro with little regrets.
Unfortunately, being a used phone, battery health has degraded to 83%. So far, it's not necessarily noticeably bad, I can still expect a bit of juice left by the time I get home from school (well, when we had physical school anyways), but out of habit, I always bring a power bank anyways.
If only Apple came out with a Dual-SIM capable Mini-phone; that would be beyond my dreams.