In order tested
Valley Splendor Supreme Blend Bird Feed $19.98 / 40 pounds
Wagner's 13013 Four Season Wild Bird Food, 40-Pound Bag $19.20 (including shipping)
Hill Country Fare Wild Bird Seed $7.78 / 20 pounds
4-04 @08:40 Swap sides, Wagner's on left and Valley Splendor on right.
4-06 @12:09 After two days, a lot less seed is gone than before and it really shows a lot more of the Valley Splendor is gone from the feeder than the Wagner's. Note though there appears to be a good bit more in the tray on that side too though.
Though I have to admit I'm seeing fewer small birds these and definitely not filling every perch as I've seen when I had Valley Splendor in both feeders so that might be a factor for you too. Compare the pics in my Squirrel Proof Bird Feeder Compare
where I had Valley Splendor in the larger feeder and a small seed only mix in the small one (because that was all you could use in it) Or this one from a couple weeks before I started the compare with Valley Splendor in both.
With these more common one with Hill Country Fare and Wagner's in the feeders.
Though this one cardinal might be a factor too.
Note I've found some even cheaper seed at Wal-mart. Given the above results I'm tempted to try it against the Hill Country Fare once I use up some of this other seed. Also thinking a mix of the Hill Country Fare and Valley Splendor might be and option too. For now I've mixed the couple pounds of Wagner's with close to 40 pounds of Valley Splendor I had left and to use them up in one feeder which might also indicate if a Hill Country Fare and Valley Splendor might be worth while.
Update 6/16/2017: The amount of seed I have been going through has really dropped put I decided to do another test with
Garden Treasures Wild 35-lb Bird Seed Bag (Millet) $14.98 / 35 pounds ( about 1 penny more / pound than Hill Country but is available nation wide at Lowes.
Left and right respectively. I also added Audubon Park 1844 Berry Treat Suet Cake Wild Bird Food to the holder under the bird bath.
You might also notice I added an upper baffle as one of my squirrels figured out he could leap from the side of the house onto the tray.
After 5 days I think it is safe to say Garden Treasures Wild 35-lb Bird Seed Bag (Millet) lost.
Also my semi flying squirrel figured out how to he could just reach a feeder with a vertical leap.
But even he thought the Hill Country Fare Wild Bird Seed was better.
And as far as I can tell no one has touched the Audubon Park 1844 Berry Treat Suet Cake Wild Bird Food. The squirrel sniffed it while crossing between feeders but gave it a pass.
BTW you can see the progress and time lapse video of the feeders in these tests at KTXLEAND28 Wundercam