the first character i made 5 stars was m!robin :>
looking forward to upgrading fir to 5 stars in 2 days as well!!
i know frederick is really loved on tumblr for a fact .. but mostly by an older female audience--at the very least though i would say actually nobody hates frederick, unlike takumi, with the difference between the two being is even though takumi is really popular, a ton of ppl hate his guts at the same time.
both of the characters have gained traction through memes, with frederick's being #1 chrom fan and a pyromaniac and takumi's being critumi, a pineapple, and the #blametakumi thing ,,, but as for the last thing you've said i definitely think takumi seems more popular because he's younger looking (nd i think most would think hes cuter/prettier as well, again no hate toward frederick this is just what i've noticed) and easier to laugh at/makes joke about and for sure the age thing. even if frederick isnt more than thirty takumi looks no older than 17 which is a looot younger. and takumi is a prince and plays a bigger role than frederick which are both factors as well. but ya the people that DO like frederick are usually super nice and easy to get along with tho which is good.