Sadly, there's no phone that has great software and great hardware. Pixels and iPhones have great software and quick updates, but they have no jacks, and the screens aren't very good, etc.
Samsung S8 or LG V30 have probably the best hardware (great AMOLED screens, jacks, SD card slots, etc), but the software might be lacking - there's some bloatware, some "me too" apps, and updates aren't quick. Although I have been told that the software situation is much better this year.
I think something like OnePlus 5 sits in the middle, almost a Nexus replacement - good (but not great) hardware for reasonable price, almost stock software, and it's kind of enthusiast phone, so it will very likely get working LineageOS for years to come.
Samsung S8 or LG V30 have probably the best hardware (great AMOLED screens, jacks, SD card slots, etc), but the software might be lacking - there's some bloatware, some "me too" apps, and updates aren't quick. Although I have been told that the software situation is much better this year.
I think something like OnePlus 5 sits in the middle, almost a Nexus replacement - good (but not great) hardware for reasonable price, almost stock software, and it's kind of enthusiast phone, so it will very likely get working LineageOS for years to come.