I have never heard of Jacksons of Hanover tea. Jacksons of Piccadilly, however is excellent tea. Perhaps it is the same thing.
Twinings tea is always excellent and has been a long time favorite of mine. With 300 years of experience and holding a Royal Warrant from Queen Victoria's time you know it has to be good. It is also available just about everywhere.
Stash tea is very good, especially for such a relatively young American tea company. I am not fond of Stash Earl Grey though. They go way overboard with the bergamot flavoring.
Lipton does not do much for me although I will drink it if nothing else is available. Even more insidious is Tetley tea, the folks that tried to convince you "tiny little tea leaves" were better.
In the tea industry, "tiny little tea leaves' equal the sweepings from the tea processors floor.
It is interesting to note Tetley is now owned by the Tata Group, India's largest private sector group with over 98 companies which has been in the news lately for developing a tiny little car which will retail for about $2.500 but will never meet Western safety standards.
PG Tips is very good tea for everyday use, I like it and buy it. Lately, my everyday tea has been Red Rose English Breakfast and Red Rose Earl Grey. I find these Red Rose products about equal to the Twinings products and at much lower cost. Even the traditional Red Rose Orange Pekoe is very good and an excellent value.