umm, it will be a while, seeing as he is requesting tier 4 armor and soul is tier 8, but yes, most good blademasters go for it, i prefer SOL, but soul is pretty good i guess. And as far as which one to get, again, i prefer tigrex, but thats only out of these 2. Honestly, neither are neccesary, just go for Hermetaur armor, then death stench, then, death stench u, then los sol, then akantor, white fatty, etc.
I only get about 5 full armor sets in the game. All the rest of the armors i get are all for the sake of collecting.
Its up to you get whichever you want.