I went through different tea phases and now I'm kinda settled on a few rules of thumb.
my favourite "international" tea is a nice Oolong tea (a Chinese white tea). and China in general have the nicest white teas and light tea.
Asian black tea (like chinese or japanese black tea) tend to taste more like "strong green tea" then what we know as black tea, and they often completely don't agree with milk and sugar.
The best Irish/English style tea you can get is Campbell's Perfect Tea (the loose stuff in the yellow tin).
Buy yourself the strainer, and even if you brew it badly, you'll still notice a difference in how much more robust, rounded and full of flavour it is compared to Lyon's or Barry's, with or without milk and sugar.
"fruit" and "herbal" teas, are mostly bullshit, except for mint. Which is awesome.
The nice "Spiced tea blends" are few and far between, which is why 'Earl Gray' is so unique; it's a blended tea that's actually well known and nice to drink. I've found Earl gray belnds are hit and miss, and often it doesn't matter how expensive the blend is, you have to just buy it and see. Sometimes the posh expensive brands are over done, or unbalanced as an attepnt to "taste posh" sometimes the cheapest ones you get in Aldi are exactly right and vice versa.
For good white tea (that doesn't involve having to import the stuff youtself)
Go to Supervalu and go to the in the local produce "fancy stuff" section, and see if they have Lily's White Tea. Its a small box for 4.99 (ouch) but it's worth it.
All her other flavours are I dunno, herbals flavour bollocks, but her white tea is the shit. Probably the best white tea you can buy in Ireland at the minute.