Julia I was saying what I like not what is best. That is why I think you have to first decide what speaks to you. My style is not eclectic. I buy pots that have a theme or as a conversation piece. If their purpose is to hold the plant I want the plants to speak.
Personally for me I like the black you have in the last pic. My eye was drawn to the plant and not the pots.
Because I do not know from year to year what will catch my eye or what will be available I have all black pots on the patio. If the pot was not purchased black I spray paint them black. So they are plain black, and head pots as my theme.
The front of the house I like white. The reason for white is because generally I use some type of tall green plant in the center as my thriller and for color I use colorful foliage plants around the tall green Thriller. My plants in the front are to close to the flower garden so White does not disappear but it dose not clash with any of the flowers. To my eye the Black would disappear.
It is all preference. Do you want symmetry?......Do you want the pots to be the star or blend?.....
Here are some examples of what my style of white looks like. This is what I have in the front.
This is at front mudroom door
Same pot used as Spring decor as a filler until the garden fills in the driveway bed.