Which citizenship company is the most reputable?

There are a lot of companies advertising to help get jus sanguinis citizenship.   Which is the most reputable?  I prefer lest expensive, but I prefer it done right the first time.  The all charge a fee to discuss the particulars with them...

I am also looking to do it in Italy as it appears from the blogs that it is easier/better, rather than flying back and forth Chicago (consulate)/Denver (me).  However I would only have a max of three weeks to be in Italy and I do not know if it is possible to do so.  Either I or the help company would have to research and get my grandparents birth records.  Generally know about where they are from.

Would like to hear from people who have actually used a company and have been successful.

Thanks.