For me it’s B, G, K, N, P, Q, U, X, Y & Z with few exceptions ([name_m]Benedict[/name_m], [name_f]Ginevra[/name_f] & [name_f]Kiera[/name_f] are the only ones).
I don’t like their shape or sound and could never use them.
What letters don’t you like? Why? Any exceptions?
I’m not fond of K. It doesn’t actually look that bad, but C is always more appealing to me. The only K spelling I prefer over C one is [name_u]Kai[/name_u] (something about [name_u]Cai[/name_u] is just off). I can tolerate [name_f]Kiki[/name_f] (I like it as a nickname) and [name_f]Klara[/name_f] (my cool Swiss art teacher’s name was spelled this way, it reminds me of her).
Not really a fan of D names for girls or K names for either gender.
I feel like X and Y are trying way too hard to be ‘out there’
The letter K. It’s just to harsh looking. Its like Killer. Ciller looks softer. 
I don’t like K names mostly. I’m okay with [name_m]Kimball[/name_m] (my grandfather’s middle names), and [name_m]Knox[/name_m], which I just love, but for girls I literally only like [name_f]Kerensa[/name_f]. I don’t like D names for girls very much, either.
I think the letter B is ugly- which makes it hard to really love my own name ([name_f]Bridget[/name_f])
For girl or boy its B. In particular Br. I didn’t think there was an exception but pp reminded me, love the name [name_f]Bridget[/name_f]. But that’s it.
girls - names that start with D or T
guys - names that start with G
Favs: V, L and names that start with vowels
I am not fond of K names either - most of which give me the “trendy vibe”, which I steer clear from
Favs though are: A, E, I, J, S
I don’t like too many names that begin with the letters…
K, N, Q, U, V, W, X, Y
I am also not a fan of K names. I think this has to do with the past (somewhat current) trend of replacing Cs with Ks.
I posted about this recently, I have a hard time likeing U, X&Y I’m trying because I think there is beauty in every name and I really want to see it… But those three are so hard. Z is tough for me to find one I love, posted about that recently too lol, but I’m searching, there are pleanty I really like though and that’s good enough I guess: for other letters it depends on gender and some I like more than others 
I really don’t like the letter C. Anytime I can replace a C with a K I will do it! Other than that I’m not a fan of F names.
Most K names look off–I definitely prefer C! X’s are actually okay some of the time, but Y’s in front or scattered throughout a name turn me off (I love the sound of [name_f]Brynn[/name_f], for example, but the spelling…!) and you can forget about a name with a Z! Most of the other letters are very hit or miss, actually. I’m picky!
I don’t really like X names!
I’m not fond of K because it’s just so much harsher than C. I also dislike P, I, and T. Something about them is off.
I lie most letters but I have yet to find a Q name that I really like. Also X and U names are usually too weird and not particularly attractive to me. The rest are fine I guess.
I don’t have any problems with the first letter, but I hate y.
Most* names that end in y, I prefer ie. And seeing any name that ends in -yn ([name_f]Madilyn[/name_f], Taralynn, [name_f]Adelyn[/name_f]) just annoys me.
I love the name [name_f]Maya[/name_f] but I still prefer it [name_f]Maia[/name_f].
I love the sound of [name_f]Felicity[/name_f] but would spell it Félicité
*Exceptions are [name_u]Riley[/name_u], [name_f]Briony[/name_f], [name_f]Trinity[/name_f] and a few others.
K.
Which is kind of funny since my name starts with K. I hate the look, I hate writing it. It’s not that I hate names that start with K, I just hate the letter K. I like [name_m]Knox[/name_m], [name_u]Kai[/name_u], [name_f]Kerensa[/name_f] and even the classic [name_f]Kate[/name_f] (prefer [name_f]Catherine[/name_f] over [name_f]Katherine[/name_f] but prefer [name_f]Kate[/name_f] over [name_f]Cate[/name_f]).
I tend not to like names that start with Q, R, T, U, D, F, J, K, or N.
I especially don’t like R, but I’m not sure if that’s because I don’t like the letter, the sound, or the names I know that start with R.
On the other hand, I love names that start with L, E, or M.
I don’t like any names that start with X (like [name_m]Xavier[/name_m]) or Z (like [name_f]Zoe[/name_f] or [name_m]Zach[/name_m])