Should i tell him or not?

You'll have to tell him, sooner or later. Sooner is better, as it gives him a chance to get over you and come to terms with things. Stringing him along for months or longer is neither nice nor is it fair.

Be kind. Use the old chestnut, "It's not you, it's me." This is not time to be nasty and enumerate faults or reasons or anything of the sort. You're just not attracted to him. You think he's a wonderful person, but you do not feel that way about him and you are not going to. Don't give him hope that things will change (because that's cruel, if there is no hope).

Be prepared for the friendship to end over this. I'm sorry, but that happens rather often in such situations. But you will have done the right thing by him, and helped to free him up emotionally to cultivate an interest in someone else.

Dump him, nobody wants a sheep tick stuck on them..

I say: get mad. He has put you into an impossible situation.

Get the courage to tell him that he is a friend and you have friendship feelings for him and you are PO'ed that he is backing you into a corner.

Then go out and find a real boyfriend and stop teasing this guy.

I know you are in adilemma situation, you are afraid to lose your best male friend if you reject him, but I stll think you should tell him, but it would be better to use a more tactful way to express it.