The HI is better in almost all respects. The rooms are better, the gym is better, the suites are better (and there are more of them). All based on recent stays.

The DT has a marginally better breakfast but the layout is quite zoo like. The DT bar ambience and restaurant menu beyond breakfast are better too.

The DT is almost always more expensive. The Junior suites at the HI with sofa beds are a good choice for families.

I would recommend skipping breakfast at both properties (even if it is free) and walking across the road to the truly excellent Pollen bakery.