You mean the BBC films? Yeah those are great.
The best trilogies ever are Human Condition, and Original Star Wars. The rest I've seen have major weak links either in part or whole.
I know everyone ("everyone") loves Dark Knight and Lord of the Rings trilogies, except I hate them both, and pretty much always have (once Dark Knight became a trilogy I had fallen out of love with Dark Knight and I always hated Rises).
I hate Raimi's Spider-Man nonsense. Indiana Jones' series isn't a trilogy. I don't like Evil Dead. Hobbit is abysmal trash. The Star Wars Prequels are eh, and the Sequels are crap. Back to the Future I only saw the first one, which I didn't love, and I have minimal, basically no, interest in the sequels. I can't think of any others. I should say me not thinking of others is because my memory is piss-poor and not because there are no other good ones. I know I've barely marked the surface of trilogies. I hated the first two Godfather films, so I won't watch the (supposedly-) lesser third entry.
Addendum; I forgot about the Dollars Trilogy, which is shiny, although I'm not a huge fan of Fistful of Dollars. It's good. I just much prefer For a Few Dollars More, and of course The Good the Bad and the Ugly is excellent.