Generally, I prefer classic traditional spellings.
Some of your "newer" spellings AREN'T tryndy spellings.
The spelling is simply how it appears in a non-English language.
In other words, Juliette is a nn for Julie which is the French version of Julia while Juliet is the anglicized (English) version.
Both spellings have been popular since the 1500s which does NOT classify as "newer".
Many of your tryndy versions are anglicizations.
An anglicized variation was created by English speakers to make a word be more like English in spelling/pronunciation- to impose "Englishness" on conquered people.
Also, you have some names that are NOT variations...they're actually completely different names.
Amelia is a form of Amalia which comes from the Latin word for "work".
Emilia comes from a Latin word for "rival".
These names are not at all related.
Caitlin of course since it's the anglicization closest to the original
Aimee OR Amy
...both are beautiful so it would depend on the surname. Aimee is French and Amy is English.
Emily because it's the traditional spelling.
Katherine OR Kathryn
...both names are variants of Ekaterina and both have been around for centuries. Before the printing press was invented, there wasn't real interest in standardized spelling. Catherine/Katherine/Kathryn is a prime example. Henry VIII had 3 wives named Catherine/Katherine/Kathryn: Catherine of Aragon, Kathryn Howard, and Katherine Parr.
...I prefer a 2 syllable version, so I like Kathryn
Amelia OR Emilia
...see explanation above. These are 2 completely different names and I like them both.
Sophia OR Sofia
...again, these are language varients. Sophia is the English, Greek, and German spelling while Sofia is Greek and Eastern European and Scandavavian.
...much depends on the surname as to which I would choose
Juliet...see explanation above
...I prefer the simplicity of Juliet
Riley OR Rylee
...I detest masculine names or surnames used for girls but for heaven's sake, don't futz around with the spelling to create a pseudo-feminine version. Rylee sux.
Jordan OR Jordyn
...see Riley. The feminine of Jordan is Jordana.
Aaliyah is the traditional spelling.
Isabelle OR Isobel
...Isabelle is French, Isabel is English, and Isobel is Scottish and all have been in use since medievel times (12th century). No tryndyness here.
...Since I find the name boring and over-used, I prefer the rarest spelling of Isobel.
Bailey
...same reason as Riley
Jillian OR Gillian
...I prefer the original, traditional Gillian but would probably use Jillian to avoid continual mispronunciation in the US. However, if I lived across the pond, I'd def use Gillian.
Alana OR Alannah
...Alana is the traditional feminine form of Alan.
Boys:
Nicholas OR Nickolas
...Nicholas is the traditional spelling.
Aidan OR Aiden
...the correct spelling is Aodh and the closest anglicization is Aidan. Aiden is just a phonetic misspelling.
Jackson OR Jaxon
...Jackson (the other one makes my eyes bleed)
Dylan OR Dillon
...Dylan is the preferred, traditional Welsh spelling. Dillon is the phonetic anglicization.
Carson OR Carsen
...the name means SON of the marsh-dwellers. Carsen is quite illiterate.
Zachary
...the traditional spelling
Rhys is the preferred, traditional Welsh spelling.
Christopher OR Kristopher
...another language variant. Christopher is English while Kristopher is Greek and Scandavian. I would choose based on the surname.
Sean is the preferred, traditional Irish spelling.
Jacob OR Jakob
...another language variant. Jacob is English while Jakob is German and Scandavian. I would choose based on the surname.
That's what happens with traditionalists.
We have actual reasons beyond, cuteee and tryndy for choosing a spelling.