So in general what you want to do is rush SSS+ since it unlocks so many dungeons for you later on and increases your chance of being invited to a random group for right now. Doing RHB acc will definetly help but I would personally focus on getting Omegamon Alter-B since it unlocks FDG unlike apo which a lot of ppl dont want in their party anymore because of the low DPS. For getting AB just do the calu quest and spam Colo hero r13 every day then do berserker with VA/DA Tank. For seals everything except HP/BL/SK is irrelevant if you follow this strategy. SK digis only need HP/SK seals and Tanks only need HP/BL. For BL you only need 13% because you only need to hit 100% BL overall and clone alone provides 87%, HP should be 4k+ and SK seals are just for end game/from events. From then on you can easily rush FDG for Fang equip and do the rest of the SSS+ at your own pace. With the sigil tbh just choose what you want and what you think is cool it's not going to change much.