Best front loading transport tha plays RB and SACD

What is the best front loading transport that plays Redbook and SACD in the 3k to 5k price range?
Do you mean purely as a transport? I don't think such a thing exists excpet for the upcoming Meitner transport. In the future you may see more transports that output a DSD signal along with redbook, but not right now. The Philips SACD1000 can be modified by Meitner to output DSD for use with their DAC.
I believe that Theta is comming out with one next month for about 4K.
Audio Synthesis modifies Pioneer DV-47Ai units for use as transports for their own DAX Discrete DAC. The Pioneer unit is a universal player and this setup (with Audio Synthesis Link option) will allow redbook, DVD-A, and SACD playback. Like the Meitner the whole shebang is proprietary. I really don't know how the thing works, but it sounds incredible (the part I am interested in). I am guessing that the Pioneer transport converts DSD to PCM and then sends this to the DAC, I am clueless however, so if you are curious, you should contact Audio Synthesis directly for specifics. The DAC displays "DSD" in the source signal area of the display, but this could be a pseudo kind of thing. Given the universal format and phenomenal performance I think it is worth a look. I love mine. I really would like listen to it right now, but alas, it is too late around my household. Audio Synthesis Website
If you don't mind spending a lot less:

Marantz SA-14 placed atop the Neuance platform.
It is my only source in my $50+K system.