What Step-up transformers are best value?

I am very happy with my Bob's Devices Cinemag step ups but I haven't used the ones you mention.

from everything I have read and heard, to get top performance from a SUT/MC cart system, they must be matched to each other. Search the archives and you will find lots of information on this. SOME carts are very sensitive to loading and some are less so. The benefit of the S&Bs is that you can easily experiment with and hear the diff btwn diff loading values and diff resistors. You might want to consider a head-amp (aka pre-pre-amp) if your phono stage does not provide sufficient gain. I have used the ZYX CCP-1 with very good results (not w your cart, but I do not believe that a head amp/cart match is as critical as a SUT/cart match. Just my $0.02, bt I'm guessing unless you can find an SUT that several people agree is a good match with your cart, you're going to have to experiment some.

I also use a headamp and do so very happily. I find it quite flexible (it has two gains and a pass-through, and 4 different loading choices). It easily beat my previous best SUT, that said it cost a bit more than the SUT did, and I have never tried a SUT with the reputation of the S&B TX103 (i.e. one of the best ever made).