Hello. I had been a SoftBank user for about three months because I wanted to experience 5G. SoftBank had the widest 5G coverage in my neighborhood, so I gave it a try for a bit, but a monthly bill of nearly 8,000 yen was, well, a bit much... so I decided to switch to the lower-priced "ahamo." Incidentally, SoftBank has announced a competing plan called "LINEMO," and au has announced "povo." Related article: I'm a longtime au user of 10 years — here's what I felt was good and what to watch out for after moving to povo
Each plan has its own appeal, but I went with ahamo.
Price and Details

The monthly fee is 2,970 yen (tax included) for 20GB. It includes 5 minutes of free domestic calls, international roaming, and data top-ups (1GB / 550 yen). This is true for all three carriers' plans, but because there are no complicated discount conditions tied to the price, it's easy to understand. With the older plans, you had things like a family discount (3 or more people), fiber-line discount, "if you use XX card," "discount if your data usage is under XX GB," and so on... I was happy to be done with the "wait, who actually qualifies for ALL of these?!" kind of situation.
The SIM Card Has the ahamo Look
Instead of the all-white card you tend to see with budget SIMs, it has a design with the ahamo logo on it. It's also printed on the back of the SIM card, so it's easy to identify.

I signed up as a brand-new customer, and it arrived in about three days. That was pretty fast. I only ordered the SIM card, but it was delivered in roughly a size-60 cardboard box, which surprised me a little. (The SIM card was at the bottom of the box.)
Speed Is Solid MNO Quality

No complaints about network speed. As you'd expect from an MNO. I often work while on the move, and at this kind of speed it should be fine. That said, in crowded times and places — like a station platform after 6 PM on a weekday — loading did get a bit slow at times. Even so, it's at a level where there are basically no problems.
Trying Out the ahamo App

The ahamo app has a clean layout — it feels like it has just what you need. On the home screen you can check the monthly fee and your remaining data.

By the way, every time you launch the app you have to tap the "Sign in with d ACCOUNT" button. When authentication is required, you have to use biometrics like Face ID or enter the PIN you registered, so it's a bit of a hassle.

Glad I Switched to ahamo!
Overall, I feel I'm glad I went with ahamo. If you can pick an MNO for around 3,000 yen, that's a good deal, and the line is solid. Back when I was using a super-cheap MVNO, it was often the case that during congested times like noon and 6 PM on weekdays, communication barely worked at all — but with ahamo, an MNO, that should be fine. By the way, the d POINTs from the early-entry campaign require an application to receive, so don't forget!