Choosing a Space Marine Chapter

My Kill Team Starter Set is arriving tomorrow. I'm a Death Guard guy but want to get my 10-year-old son into playing with me, so this is perfect because I will get to let him play the Space Marines. I also co-run a Warhammer Alliance Club at the school where I teach, and a lot of the kids got Kill Teams for Christmas, so we will start playing it in the next few weeks in which I'll be able to play the Space Marines and/or Death Guard depending on who I feel like and am fighting against.

So, I'm trying to decide what to paint my Space Marines as. I want something that goes well with the green of the Death Guard army so that when my son and I play, it all looks cool together. So, not Dark Angels or Salamanders which are just more green. But, I'd like something with some cool lore, too, because I'm a lore fiend.

So, Blood Angels (or Death Company), Void Tridents, Necropolis Hawks, Imperial Fists, Dark Krakens, or even just the Ultramarines would all be great choices for their look.

Dark Krakens & Void Tridents are appealing to me because of their "ocean planet" vibe and because they are lesser known.

But, if my son gets into Warhammer 40k, I know he'll want to have lots of stuff about "his chapter": Funko Pop figures, shows to watch, etc. So doing something well-known — even Ultramarines — would be a benefit in that regard.

For that reason, the Death Company, Blood Angels, and Imperial Fists work well.

I'll ask my son, too, to get his ideas/input, but I appreciate all your input as well.