Bowyn
As far as I'm aware, Bowen is the more common spelling of this name. It's a nice alternative to Owen or Rowan.
Lloyd
I don't think it's due for a revival yet.
Noah
I really like this choice but the problem is that many others will too! It's certainly the most popular of your choices.
Willoughby
On paper, this name looks great. It has a lovely, mellifluous sound to it as well. However, it's a bit of a mouthful for a name and quite flouncy, especially for a boys' name. I think William, Wilfred and Wilbur are better choices.
Isabella
This is a gorgeous name but it's a bit commonplace. Personally, I'd be inclined to use something a bit different (i.e. fresher sounding) - maybe Arabella, Annabel, Estella, Christabel, Gabriella, Fenella, Mabel, Isadora, Mirabelle, Isabeau, Raphaela, Susannah, Cassandra, Seraphina, Juliana, Eliana, Georgiana or Liliana - but if Isabella is the frontrunner, go with it.
Lily
Lily is pretty but it's a bit insubstantial. It doesn't sound like the name of a strong, independent woman to me; it's just a bit too delicate-sounding. If you like Lily, you might also like Willa, Liliana, Libby (as a nickname for Elizabeth), Elodie, Amy, Amélie, Cecily, Emily, Millicent, Pearl, Lucy, Sophie, Sadie, Audrey, Kitty (as a nickname for Catherine), Felicity, Rosalie, Ruby, Alice and Verity.
Seren
Apparently the only Welsh name people know at the moment. Of course It's lovely but it's a little bland! How about rediscovering Megan, Ffion, Bronwen, Angharad, Myfanwy, Lowri, Nerys, Sioned, Delyth, Dilys, Carys, Cerys, Nia, Bethan, Elin, Catrin, Ceri, Catrin, Rhian, Gwen, Anwen, Eleri, Glenys, Eirian, Gwendolen, Lowri, Meredith, Tegan, Mali, Rhiannon, Haf or Sian?
Willow
See Lily. How about Willa, Rowan, Violet, Hazel, Olive or Laurel?