I’ve spread my emblems out to some extent and must say I’m very happy about that choice. I still take down 4300+ raid defs with my >4000 attack teams - doesn’t really matter if the defenders are +5 or +9.
That said, you’ve got good options. I don’t see that many healers though, and Mel is indeed flimsy when naked. Zim is a force and Druid serves her very well, but right now maybe Mel would make better use of the emblems? Caed is not a bad choice (I’ve got him +10 and he’s in my 3-2 attack and green mono, gets lots of use) but for you Mel is probably the way to go.
I’d also go Tiburtus before Alasie, right now. You can always do +10 for a 4 and then start on a 5. It’s so much cheaper for 4s and it makes so much more of a difference. I’ve kept the emblems on all my 4s except for the odd one being replaced completely by a 5 (my beastly Grimm got stripped to feed GM and Kage after I got Athena).