I chose the DMM6500 at work (I’ve used the 34465A and don’t care for the UI), and I’m quite happy with it. It does have some UI quirks, but it’s fast and powerful, and incredibly flexible. I haven’t used this feature yet, but one thing you can do in it is write your own apps, so you can make it do things it was never designed to do. One of the demo apps is a fully parametric thermistor readout, so you can make it work with any imaginable NTC thermistor.