looking for photo college

Not sure if the best, but I've always used PhotoGrid or PicCollage. But if you only want that, most newer phones include a collage option in their stock picture editors.
 
Not sure if the best, but I've always used PhotoGrid or PicCollage. But if you only want that, most newer phones include a collage option in their stock picture editors.

I think I've used PicCollage as well. Whichever one that you can link with Instagram.