I had a similar feeder and filed it with sunflower seeds. I mixed it half and half with black oiled sunflowers seeds and shelled sunflower seeds (out of the shell)
Now let me tell you the down side so you are prepared.
1)The seed husks made a mess and landed on everything stored near it- BBQ grill, chairs, hose. The expensive shelled seeds are clean but are attractive to critters.
2) Squirrels could reach it by jumping from the roof. They would tear it off the window every few days. Maybe you will not have this problem.
3) My feeder was south facing and exposed to the sun. No matter how I cleaned the window or softened up the suction cups per instructions the unit would eventually break free causing it to fall (if the squirrels didn’t get it. ) I got so mad I used clear epoxy and glued it to the window. That worked.
On the positive side, it was amazing to see the chickadees up close and personal.
In the end was it worth it? Yes, for a year. It was fun taking pictures for a while. My feeders are now well away from the house.