I have used but don't own a pair as shown in the link below. Using the double barrel sleeves that are sized appropriately to the diameter of the line work best. That is rule #1 when choosing the sleeves. Single barrel sleeves (I think) should be used with the wire. I have the other style of crimpers that tend to crimp (fold or pinch really) from one side and they are an entry level crimping tool. IMHO, those may be more appropriate for smaller targeted species but the crimpers in the link are better for the larger species. I am sure we will see quite a few of the guys who go for the big horses chime in to tell you how they are successful. Don't be fooled into buying the cheap ones if you intend to go for some large fish or sharks.
I prefer the Jinkai SC-3 for my crimping its inexpensive and adjustable. I use the appropiate sized jinkai aluminum sleeves for my flouro/mono leaders. I have found its easiest to stay with one brand of crimper and the same brand ofsleeves no matter what brand it is.