It doesn't really depend on gender, it more depends on personality.
I don't know what gender Leonardo is, but I would presume a buck. In terms of bonding, it can be easier m/f, then f/f, then lastly m/m, but there are no guarantees doing it like that.
You might be better off taking him to a rescue and letting him choose his own friend, that way you stand a better chance of bonding them.
You might find it easier to observe him where he is naturally because it might give you an idea as to whether he is dominant or submissive. Whichever you he is, you ideally want the opposite, if he is dominant, you want submissive, if he is submissive, you probably want dominant, but that's not quite so key when it's a submissive bunny.
If you do get another rabbit, you need to be prepared to house them separately if necessary because bonds don't always work. Also, read up on everything you can about bonding before you go and get another rabbit (theres some greta stuff in the Bunny 101 forum).
Good luck