That crest is very characteristic of a goldcrest. I know of two sub species of gold crests, one has the yellow stripe the other a slightly orange stripe and body
This seems to me like the goldfinch, regulus regulus. Not the common firecrest , regulus ignicapilla.
My information sources is the Merlin Bird spotting app.
EDIT: the correct name is not goldfinch but goldcrest. As it is not in the finch family at all.
I probably should have said where i am located, it's in Düsseldorf, Germany. Regulus regulus should be around where i live too, according to my local bird book, but i have not seen one yet, i am quite certain it must be the child of Carduelis carduelis, European Goldfinch, the older ones are all over the feeder:
Carduelis Carduelis, one of my favorite birds. They sing amazingly (plus they're cute). My mother doesn't use her lawnmower too much or at least leaves some areas untouched, so it's not rare to spot those birds. I've seen up to 20+ at the same spot, eating on the ground or relaxing in apple trees.