> Carriers supposedly prioritize their own customers

They explicitly do, even among their own customers and plans. If you Google the carrier name plus QCI, you’ll find tables where people have documented, which plans are in which priority group

Mint (T-Mobile MVNO) has been great for me, $20/month/line and my one experience with international travel was good ($20 for 10 days). I used to be on Verizon and the quality of service doesn’t seem any worse while the price is dramatically lower.

eSIM transfers are an absolute nightmare on T-Mobile. I recently did two of them and both times, the transfer started but never finished, so I ended up with no service on either device. That means no ability to call their support line and no ability to receive the confirmation SMS they use to verify you are the correct person. They also immediately permanently nuke your physical SIM card so the only way to go back to sanity is to purchase another $10 physical sim card or get one of the physical sim cards that you load eSIMs onto (I did the latter so it won't self-destruct every time I do a transfer).

1. They only do transfers through their native app, not on their website. To log in to their native app, they will do SMS verification. So I sure hope you are still logged in before they lose your eSIM and leave you with no service at all.

2. If you are able to get into their native app so you can access their tech support, their AI chatbot will flat-out lie to you and tell you that T-Mobile cannot send you a QR code to download your eSIM (even though T-Mobile's own website states that they can). If you ask politely for a human, it will resist. I've found "connect me to a human you worthless fucking bot" is the secret passcode to get a real human.

3. If you request they send you a QR code, some of their support staff will ignore that request and still try to initiate the transfer through their app, so clearly requesting the QR code is not a common procedure.

4. When you request a QR code, even though you provide the EID, they will ask for an IMEI number. They then generate the QR code for whatever EID they have associated with your IMEI number in their database, completely ignoring the EID number you sent them. They did this to me _three_ times. The only way I managed to break the cycle was I sent them an IMEI number for a phone that was never on their network so they'd finally listen to me when I told them my EID number.

I'm never buying a phone without a physical sim card slot again. There's nothing wrong with the eSIM technology but the carriers have decided to make it as miserable as possible. The hardest part about transferring a physical SIM is finding a paperclip.

> But also, which MVNO should you go to? Carriers supposedly prioritize their own customers, so it feels a bit like running on spot instances.

If you are so paranoid, just get multiple SIMs? Most phones support that these days, especially multiple eSIM. And the plans are really cheap (at least where I live).

Ive been happy with US mobile - you can actually switch between their VZ backed network or their ATT backed network.

Personally switched from VZW to Google Fi. It's on TMOs network. As you can imagine, when engaging with Google's support was hilarious when there was something I needed, but overall I don't miss Verizon and pay drastically less.

US Mobile gets you QCI8 (same priority as Verizon postpaid) when you're on the Verizon network with a 5G device, and they let you pay for QCI8 on AT&T.

I was able to transfer eSIM for a lost phone using their website, I think the online carrier had run into that issue before.

They're all fungible if you aren't addicted to your phone.