Yorkshire Gold is distinctly better, Tetley and supermarket own brands are mostly about the same: OK depending on your taste, a couple of supermarket and Twinings that are a bit crap. There are cheaper brands that are awful. PG loose leaf is a refreshing blend, far better than bags, but it's not a premium tea.
The tea bag problem is mostly not enough tea and 1-2 minute brewing dust can't give the flavours that take 4-5 mins to come out. That and they all reduced the weight of the packs for the same number of tea bags. 20 or 25 years ago they all increased the number of tea bags for the same weight of tea.
Even slightly premium loose leaf is vastly better. e.g. Tesco's cheapest Finest - the non-estate specific one, or Booth's quality loose leaf is leagues ahead of PG loose leaf, let alone bags (and cheaper!) etc.
Locally I have a bloody marvellous specialist tea shop with far, far too many excellent own blends. :)
Isn't PG generally considered to be one of the poorest quality teas available in the UK? (it sells well, but that's mostly because it's dirt cheap).