I would go with the gruul because the rats deck can only be modified in so many ways where as you have a lot more room to toy with creatures in the gruul deck.
February 5, 2019 7:50 a.m.
Hum... really depend on what is your type in EDH. Gruul offer more diversity for sure, but sometimes, it's all fine to go monocolored ( as long as you accept that youll have problem to remove some threats...) Also depend on what kind of EDH or meta you're planning to play with your deck. If it's casual, all fine pick the one that you think will be the more enjoyable to play(that is the way I go now, find it more fun with my playgroup). As for cEDH and playgroup with superduper deck, well, that might be a problem. Anyways, if you pick the rats one, think about maybe adding a Skullclamp :P But the important thing, have fun. Let us know your pick !
February 5, 2019 4:35 p.m.
Gruul. More options = more fun. Rats can be fun, but so narrow. Once you've done it...
Also, what griffstick said. You know what black sucks at? Artifact/enchantment removal.
Obviously not all decks run these cards, but it's not that difficult to get locked out entirely, never mind not winning.
February 7, 2019 12:32 a.m.
If you want to run a consistent deck then you'll need Thrumming Stone for rats, personally I would go rats just because it's something which I would enjoy more.
On the other hand, you have better options to upgrade the gruul deck and have a better deck by slowly improving it!
You need to way up how invested you are into both and which you would enjoy more :)