Hello my good dude. I am learning french in school, and esperanto outside of school, and I can tell you that the connections you'll make between EO and FR are incredible. There are a lot of cognates, and if it isn't a cognate with EO, it may be a cognate with English. I have always heard of latin as being quite difficult? And I think, but am not sure, that there are not a great ton of cognates between latin and EO. I think EO uses some root words from latin? But not many cognates as it is technically a dead language.
BUT! No matter which lang you choose, you need to keep in mind what you're up against. Esperanto is designed for easy learning, French? Latin? Not so much. So don't expect to fly through the lessons like in EO, and don't expect every element of the language to makes sense. There will be irregulars. As well as absurd, unhelpful grammar rules that could only possibly make sense to a native speaker.
But don't get to discouraged by that! In my experience, once I got about 3 years into french(we take it slow in school, for sure), I started to be able to just say "welp! If it sounds french, it probably is!" and then guess for irregular spellings/conjugations with about 50% accuracy. So it does get easier, just don't get too discouraged.
Also some good ol' fashioned studying can really help ya out in French.
And you're probably right about a Euro lang being an easier step from EO. However I have tried out JP courses and can say they are not as hard as everyone says??? Just letting you know.
Ĝis la revido!