The best dual SIM phone is the Moto Z Play which is only 250 USD with the coupon motozplay on banggood. It has a landscape keyboard coming! You can find the keyboard on indiegogo. No links -- I do not intend to spam. Finally, finally, finally! Five years since the last keyboard phone, the Droid 4. Instead of the keyboard, you can also add an additional battery pack -- while more expensive than a generic USB battery pack, the lack of wires is a serious plus. In this it's also like the good old days when batteries were replaceable and some companies provided seriously larger capacity batteries and a new back which made the phone look like a camel the moto mods battery packs look better. But also, the Play version of the Moto Z has a pretty good battery life in itself. There are mods but those are IMO gimmicks. The zoom camera mod totally missed the price/performance spot for example.

There are rumors that a new moto mod will include 4 SIM slots