Bro, I need splitter, that exo is a godlike exo. Like WOW, grats again. Im a huge fan of splitter now even tho we haven't seen it yet xD/
For me personally, I think Lightning Blades is the best all-around exocore A long range skill that ensures free combos/juggles (op in teamfights), and an invincible launcher (and can also groundhit) for 1vs1 scenarios Many exocore tier lists disagree but I find Lightning Blades one of those exocores that really stand out in terms of power [in both 1vs1 and teamplay]
mecha strike is the strongest exocore in the world. nobody says so because people are usually not in the mood to talk after being crushed by the weight of a mountain. the raw, destructive power of its overdrive skills—giant swing and giant knuckle—will surely make you regret crossing paths with a wielder of the legendary mecha strike.
Did you mean Thunder Blades? I feel Thunder Blades is very good like you said but it just seems to me boring.
Out of exos currently in-game, I'd say the easiest to use would be Thunder Blades, Shield Cannon, the Berserk Sword, or the Ice Rifle thing. I can't stand by anything being the "Best" because that is completely relative and opinion based.