Hannah:
I personally like until we meet again more, but that’s because I am more of DeanPharm person and I loved the idea of these reborn soul mates refinding each other
My feelings exactly. This is such a powerful theme - and of course, Ohm & Fluke were fantastic.
I also love "Between Us" - for the reasons you say, but also because it does a really good job of expanding on "UMWA" without too much repetition or (even worse) awkward retconning. (There are a few scenes that are glaringly taken from "UMWA", easily recognisable because Pharm's hair is so different - but that's a minor point.)
Hannah:
We really haven’t seen that plot a lot in BL done and done correctly in my opinion
Oh ... add "Century of Love" to your PTW list right now!
There's also "Once Again" (already on your PTW list), although the ending left me unsatisfied.
"First Love Again" (which you already watched) is also a pretty good treatment of the theme (and Jeon Changha is such a cutie!) - although you're right, none gets it quite so right as "UWMA".
P.S. @Hannah: If a post is too long to quote, just quote a little piece by selecting the relevant text and clicking "Quote" right above it!