Emma:
Does anyone know an effective way to decide on what I should watch next? I mean, I have so many series in my currently watching and on-hold lists so maybe I should start with those? But I feel no pull towards most of them.
Your PTW list is indeed impressively (*cough* insanely *cough*) huge. I see some excellent BL titles there, e.g. at a glance Thailand: "Until We Meet Again", "My School President", "Moonlight Chicken", "I Feel You Linger In The Air", Taiwan: "About Youth", Korea: "Shoulder To Cry On", "Blueming", "First Love Again", "Eighth Sense", "To My Star", China: "Stay With Me", Japan: "Takara-kun to Amagi-kun", "Perfect Propose" and many more).
But I don't know your tastes and preferences, or what you're in the mood for right now, so it's hard for me to give specific recommendations. I also don't know if you have any subscriptions (especially Viki, Gaga, iQiyi).
I see that you gave 10 stars to "I Told Sunset About You", so you might especially enjoy the sequel "I Promised You the Moon" (in which case I would recommend first watching the special bridging episode "Last Twilight in Phuket").
Beyond that, here's my general advice:
(1) Sort your PTW list by "Score" (average MDL rating), look through the top-rated titles (or at least > 8), and see what grabs your mood right now.
(2) If it's a BL that you're in the mood for, read back in this forum to see what other people have been talking about (which, of course, tends to be current and recent releases).
(3) Use the "Priority" field in your PTW list to remember the ones that are more or less interesting to you. (This was great advice that someone gave me a while back. I just regret I didn't start doing this earlier.)