This four-color deck is hard to discern based on the Commander cards alone, mainly because each of the cards abilities are quite different, so this may be a case of picking a preferred Commander and making some upgrades/changes to build better around that card
Sylvan Library Arguably the best green enchantment (although die-hard fans of Food Chain are welcome to disagree), Sylvan Library is also among the best card-draw spells in MTG
Sure it can make a swarm of Phyrexian Golems, but that's after spending nine mana to cast it and 12 mana to use the Encore ability
Seedborn Muse Getting access to four times as much mana as everyone else is so much funfor the person doing it
They arent the explosive, hand filling draw, and they arent rituals or ramp, producing only a temporary mana advantage
Thanks to the way its designed though, you can do a lot more with it, especially since a +1/+1 counter will take off the -1/-1 counter and allow it to persist again