I haven’t watched anything yet, I’ve been more into manga lately but I’m sure I’ll be watching some of the new seasonal stuff that’s about to air and also finishing some anime on my list still from last year.
I was in the middle of SAO when the new year started, was actually watching when it turned 2018... not a very good anime...
For a full series start to finish in 2018 the first one I've seen is Mononoke, which I thought was pretty good despite a few headaches the animation caused :)
CLANNAD AFTER STORY
I started on the 30th december 2017 and finish exactly on the 1st by 2am
dang, the most emotionally intense part is right after 12am. While others in my town are playing fireworks, I am here crying...
I finished Sakura Quest.
If you're asking what's the first anime of 2018 that I've started from the top, then I haven't started anything yet. I'm actually more interested in that, otherwise it just feels like... oh, new year and you're still finishing the same ol' stuff. Not a good feeling, to be honest, but I'm almost caught up on Summer 2017. I'm so behind.
Started watching Death Parade. It's out for quite some time, and I never got a chance to watch it, since I have so much to catch up with. But seriously, it's so good, really enjoying my decision to watch it as a first anime of 2018