[Help] How to connect corner 4x6 beams on 6x6 posts

I'm working on a deck: the frame is 8'x8' of treated pine, and the top is cedar. I'm going to use 4 8" concrete piers set below the frost line (one at each corner), with the bottom of the piers flared out slightly to give it better footing.

6x6es will go on the piers, then 4x6 beams to make a square, then 2x6 joists at 16" centers for the rest of the frame.

For something like this, I see I have some options, which are not limited to (disregard any sizes in these pictures, just for illustration):

Simple L brackets

Mitered corner bracket

Lapped corner, possibly with one of the above brackets

Thoughts on this? It's not going to show in the finished product so it doesn't matter what it looks like, just that it will be sturdy.

Thanks in advance.