Beelzebub, being the Avatar of Gluttony, is always hungry. Despite appearances that he thinks of nothing but food, he is emotionally mature and wants the best for his brothers. He loves his family more than anything — even food. Family is his number one priority and he has a big soft spot for his brothers. Not much else can be said about his character as that makes up the majority of his personality. Beel (I personally pronounce it Bee-L, but i've seen other pronounce it Bell as well) has little emotional range (except when angry). So this will be a harder part to play in my opinion as you want to avoid sounding monotoned while accomplishing this goal.

Please check out this really short clip to get a feel for his voice: https://www.youtube.com/watch?v=NmX2bZx-Y5w (there is also some shorts that Obey Me has released that you can watch as well if you would like to get a better understanding of his character). 

In my opinion: His voice is going to be a medium-deep voice. Nothing overly special about his voice. A MUST IS THAT YOU HAVE TO BE ABLE TO DO EATING SOUNDS CONVINCINGLY.