Fuchsias last a very long time here, lovely flowers until December.
Petunias: there are now varieties that don’t need deadheading as they are sterile, look for the ones called “Vista” (limited colours available).
Aubrieta is great for spring colour, very intense violet.
Patio dahlias (like the ones from the “Gallery” series) are compact and good in pots.
Californian poppies are just gorgeous and easy to grow from seed in situ.
I’m partial to a scented leaf pelargonium or two, I can’t quite explain why I like them so much… they have a lot of personality 🤷🏼♀️
I’m trying to grow tagetes (African marigolds) from seed for the first time, fulling embracing the retro vibe of orange pom-poms.
Impatiens, surfinias, Calibrachoa, lantanas, nicotianas, begonias are other options depending on light level/soil moisture.
Do you have large pots? Do you like to feed and water regularly? You could grow cannas or Brugmansias, both grow huge and spectacular.