One thing I personally don’t like with latest Dual SIM phones is the combined (hybrid) card slot for Micro SD and nano (micro) sim card. In that way one need to choose between dual Sim capability and extra storage space. To be honest, I mostly use one SIM card, and rarely have a need for second one, so the other slot I use for microSD memory card. However, it would be nice to use one for calls and other for data since some operators have SIM cards with great data monthly plan. In that case, I can’t extend my internal memory with tons of music and photos that I take on daily basis.
Nokia 6 has dual-DIM capability but uses combined, or hybrid card slot. It was probably much more difficult to open another hole in the beautifully designed aluminum body of the Nokia 6, so partially I can understand the use of one slot for all the cards. Maybe they could have made the slot wider like in Nokia Lumia 1520, so we could have a bit bigger opening that could house two card slots. But, the question is how would that affected the structural integrity of the aluminum body.
On the other hand, Nokia 5 and Nokia 3 have separate micro SD and SIM slots for Dual SIM version of the phone, which is quite nice feature.
So, if you don’t like hybrid slots go for Nokia 5 instead.