It really depends on what are your objectives of taking those exams. Do you just want to pass it or do you want to learn the skills?
I took 12 MS exams so far since 1998. In the beginning I used Transcender to prepare my MCSE 4.0 exams. It was almost impossible to fail. I did pass all 6 MCSE exams quickly with little hands-on experience.
But now my objective of passing exams is to simply learn the stuff, so I think all major test prep vendors are good. Now I use Self-Test and Measure-UP because those are provided FREE at Microsoft.
I used Skillsoft products before for other IT vendor exams and I think was good too.
So to answer your question, Transcender might be easier in terms of passing the exams, but my advice would be to use your existing resources (e.g. Skillsoft) for now. Don't rely too much on those test prep software, they are meant to be a study tool
in helping you learning the real stuff.
Good Luck and Best Wishes!
Thanks, Michael Mei