Luminor for me.
First because of size, it's hard for the skinny-wrist-contingent to pull off a big Radi without looking stupid. At 7" the highest I'll go in any watch is 44mm, and even that's a stretch really.
Second because it's more of a sport/activity look which is better for daily use. The Radi to me is more elegant, with a slight throwback look, versus the more modern hard edges of the Luminor.
In a perfect world we all have rose gold Radiomirs for black tie/formal events, and sharp stainless Luminors for the day to day work at the office. That's how I see it.