i would actually start with guitar. i don’t know about others, but i find it more difficult to play uke, but maybe cuz i have big hands. it just feels really uncomfortable to get some of those chord positions. plus, the tuning is totally different from a guitar. if you learn guitar, you could even get a “ganjo” (a banjo strung like a guitar) when that craze starts…or doesn’t, haha. i think if you ultimately want to play guitar, learn guitar. just my $.02
[edit: and this is coming from a monkey who never took a guitar lesson, only piano]