Dillan looks like it would be a good choice, because the y is very trendy nowadays. However, I would much prefer
Dillon over Dillan, but I loathe
Dillon as well because it reminds me of the surname.
Dylan on the other hand is how it is spelled in Welsh mythology, which dates back hor far? This is my reason for saying
Dylan is the "traditional" spelling, and I really prefer the traditional spelling of (almost) every name. (Exceptions would be replacing some Ch- with K like
Kristina - but thats probably because its my own name).