Neither, I would look into Vox's Tonelab LE. I own both the Pod XT pro and the Tonelab LE. I first got the Tonelab LE and to my surprise it is very reactive, it behaves somewhat like a real tube amp. At first, I tought the Valve Reactor thingy was more a marketing gimmick, but turned out there's definetly some mojo to it.
I don't give a rat's as* if the models are true to their origins. I was interested in good tones for recording. I can honestly say, It sounds good and feels like an amp, in an organic saturation kind of way. It might be a little trebly, but which modeler is perfect anyway, let alone a real amp. I also have used it with cab emu turned off and feeding the power amp input of my fender ultimate chorus dual combo amp, basically bypasing its preamp, with very good results. It is really great either way, directly, or by using a real amp, bypassing its preamplifier, or using an amp that has line level inputs. I get tons of great tones without much tweaking.
I used to take the Tonelab back and forth between home and the studio, as I used it at work a lot, but also never wanted to leave it there and have no fun at home. So, as a suggestion from a friend and based on reviews, etc, I recently bought a POD XT pro rack to leave something at the studio, and not have to drag my Tonelab all the time. Well, my expectations were very high for this one, because of all the hype it gets, and I felt somewhat dissapointed. I mean you can get some decent sounds for recording, but the mojo is not definetly there, at least for me. My assistant also agreed with me without even priorly sharing my opinion with her. So that tells me I'm not crazy either
It just doesn't feel like as reactive as the Tonelab, even the FX, for my taste do not sound as good as tonelab's. Now I'm more into clean and crunchy kind of saturated dirty tones, but with the tonelab I've been able to get good overdriven sounds too without getting deep into that territory. For clean and crunchy is awesome in my opinion. But with the pod XT, its just fizz land when you go to eleven. I don't know, I've been tweaking it a lot, trying to find great sounds, but it just feels like a cheap EQ'd sound. I've been able to get some decent clean tones, and some crunchy tones after much tweaking, but not as good and as easy as with the tonelab. With the tonelab, at least for me (I now the flames might be heading this way already), any amp I try, it just a matter of doing some little tweaks here and there, turn the treble control a little bit down on my deluxe strat and I'm in heaven. Then just for shakes I switch to another cab, little tweaks here and there and I find another very usable tone that puts a big smile in my face. Not all of em work, of course, but many do. Much less options than the XT, but much more easy and fun to get good tones by doing small tweaks and still keeping it simple.
But you really have to try it for yourself to see what I mean. Go to GC or whatever, pick a good guitar and try it for yourself. Try to plug it directly into a line level device or digitally via SPDIF into a recording setup with nearfields, without an amp, or, try it with a keyboard amp, or to the Stereo FX returns if all you have handy is a guitar amp. Read the manual to get a feel of the Valve Reactor circuit and how the knobs affect its response regarding the emulations.
Just my 2 cents..