>>96816677
Ultramarines are unironically a good choice for both hobby or fluff, their super special character trait is that they're extremely competent. They have a strong color scheme with lots of prior examples to mix/match/make your own.
Crimson Fists are a chapter I just like, easier to paint too.
Space Wolves are balls-deep in wolf and pop-culture viking esthetic. If you like that, great, if not then they have little else to offer but their new models are nice.
Chapters with more divergent doctrines like Raven Guard and White Scars are cool, even as successors with your own color schemes.