Are you looking for one with seasonal change or year-round gold?

Oh, I consider all options, with seasonal colour variation or otherwise.

It is for a small gardenbed where I already have the bluest of all light blue (Colorado blue spruce) the bluest of all dark blue (Blue Star juniper) the greenest of all chlorophyl green (Balsam fir) all of them are dwarf conifers. I thought that a most golden dwarf conifer would provide a nice colour contrast, we'll see.

Borderline hardy for you but Chamaecyparis obtusa 'Nana Lutea' is a possibility.

Ontario, you’re not giving us a lot to go on, but since you’re growing spruce and juniper, I take it the site is mostly sun and the soil well drained. You could take a look at Thuja ’Philip’s Magic Moment’, which is a nice yellow-gold and is slow growing. I tried one, but the deer made it a brief experiment. If you like a garden challenge, you could try Abies nordmanniana ’Golden Spreader’. It would be pushing the boundary for your zone, but could be spectacular.

Yes, it is a raised gardenbed with good drainage in full sun. Blues and greens love it there, but there may be too much sun for some goldens. I actually lost a Chamaecyparis obtusa 'Butter Ball' at that exact same spot. I am thus looking for sun-resistant gold :-)