'Best' is subjective, but humans are the worst; they get nothing a Barb doesn't already have.
Now, a Wood Elf is very quick - which is what I really, really like about them. With added Barbspeed you at least have to worry less about actually getting your melee fighter in melee. If anything, that's what I struggled with in EA. Laezal could do all kinds of awesome stuff... If she were in range. Often, she was just wasting rounds and being arrowbait.
But, I feel weird running a STR based Elf and will probably never do it.
Next.
Halflings never roll ones on a D20. That is awesome for a damage build that hits often, so especially if you go dual-wield. Critical misses happen quite often, but the halfling negates that entirely and become even more reliable.
But, I feel weird running a STR based Halfling and will probably never do it.
Next
HalfOrcs have increased Crit Damage. I like that. Big numbers are tasty. Like chicken. Which isn;t all that tasty on it's own, actually, but with some seasoning it becomes tasty. That's what I mean.
I don't feel weird running a STR based HalfOrc *at all*, they're made for it.