>I don't have much experience with Sigma glass. Would you rate >it equal with top named brand lenses?
There isn't a simple "yes/no" answer to that question; it can only really be addressed by comparing a particular Sigma lens against the equivalent Nikkor.
Some Sigma lenses - and not just recent ones like the 35mm f/1.4 - have garnered great reviews and perform every bit as well as some Nikkors. The 120-300mm f/2.8 EX is one example, and their various Macro lenses are up there as well. As well as that, Sigma offer several models that simply don't exist in any of the OEM ranges - like the new 18-35mm f/1.8 DC
We're getting way off-topic for the D7100/D7000 Forum - much more information on lens options may be found over in our Nikkor Lenses and 3rd Party Lenses Forums.
Thanks to everyone for the input. This thread will now be closed.