Everyone knows his main problem is that he cannot join any units, so playing with him presents unique challenges.
His statline is also something special for Space Marine players to toy with. WS8, S5, T4, W3, I6, A5, Ld 10 and a 2+ 3+ save. Importantly, he has the Eternal Warrior rule to save him from that toughness 4 stat. He gets to re-roll against an opponent HQ (Avenging Angel) which might be handy with the new missions. He also gets to soup up a sergeant which also may be helpful with challenges.
Let's get to the analysis!
Sanguinor. I love seeing the living Land Raider drop onto the tabletop. He is quite a bitch, but you shoot him he falls over same as the rest.
If anyone remained largely unchanged by the passing of millennia and gaming editions it was the Sanguinor. He's still the lovable T: 4-nearly-300 point figure he was, and I mean that for better or worse. So how did he change in 6th? Well, he has a 2+ save... Which is about it. Except now he can issue and receive challenges, which means he won't get bogged down by a torrent of attacks... Except any smart opponent will just refuse the challenge and then, well, bog him down with a torrent of attacks.
Again, for better or worse the Sanguinor remains largely the same as he did before. Nothing in this edition seems to have drastically changed him (though Overwatch did chink his armor slightly). So in the end he will continue to see the same use he did before, without much of a tactical revamp as some of the other character received.
Yeah we all know this guy was a bit meh in 5th and to be honest, he's only got worse in 6th. The glaive encarmine is now AP3 meaning the essence of sanguinius himself simply bounces off terminators... really. Yeah keep him for fun games but at 275pts don't expect him to be anything more than average. The only thing I can think of which is useful for him to do is buff your units and go around challenging characters with his 3++. But he's still nothing special.
Sanguinor even more of a bad joke now: easier to torrent away and his weapon is AP3.
If you are going to run him, you better figure out how to keep him safe until he can get into combat. You can't view him in isolation when you have a Mephiston of comparable points or cheap Librarians. Maybe by playing around with him you can develop a way to use him and drop a tactica.