If you're looking for a space marine guild, Jura's Crusaders are recruiting.
Greetings, I noticed you're looking for a Guild. If you'd like I run a Chaos Space Marine of Word Bearers: https://forum.eternalcrusade.com/threads/sons-of-lorgar-unite.3567/
We're friendly to new members, franchise and lore. We'll even help you out. If you're interested in joining just drop on in. The front page has details about joining us. If you have questions for me just ask.
I went ahead and joined. You guys seem like an awesome group and sound like the kind of guild I was looking for!
Welcome to the guild. To answer your question: I honestly would prefer if you would stay in either /or Guild. It would be less stress for you, being in multiple guilds for different races. There will be Guild event nights for E.C., where we'll all get together for some epic combat
Then consider me another of Lorgar's followers!