There are a number of versions of the XTC, so you would need to know they are different. There were fairly recently 2 different versions of the 101B (I believe the date the original was revised was in 2004). In relation to that revision, the only difference I am aware of is on the red channel. In the earlier model, there was less red channel compression and there was more on the revised amp. There is also the Ecstasy 101A (6L6 tubes vs. the EL34's in the "B" version), the Ecstasy Classic (more open sounding, much less gain, and the overall consensus from what I've read seems to be that it has superior cleans but that the blue and red channels are ususally not as favorable-- though some people disagree about the distortion channels being worse, as it is all obviously based on personal taste). There is also a rare Ecstasy 100(A or B???) version, etc...
I have only played the pre-revision 101B, and I absolutely love its sound. I played through the Bogner 2x12 oversized cab, and it sounded amazing. (That cab smoked the Mesa Recto 2x12 I also played the amp through, in my opinion-- sounds MUCH more organic and full). The cab will make a big difference.
The Bogner sound can go from what I call a very nice clean (though not quite up to par to... say a Matchless, but still VERY good when you adjust it to get "fender cleans," which is a trick with the EQ and gain knob settings that is on the Bogner forum which VASTLY improves what I think was already a good somewhat chimey clean. The blue and red channels are amazing-- a darker, organic sound-- very full. Red can get very brutal. Very brutal. An amazing rock amp, if you want a somewhat darker, organic sound. I also never found the bass or low end flubby. I played through a PRS Custom 22 and a Gibson LP studio. I know many country players use the 101B, too... but it has absolutely no problems covering light rock, extremely hard rock, etc...
I've never played any other Ecstasy models, love that 101B. Now, the SLO-100 was also suggested, above, in the similar price range. That amp is also an absolute beast. Even more harmonics than the Ecstasy, and I love the crunch and the clean channel. Less versatile live, since it's 2 channels and Ecstasy is 3. Not as many tone tweaking options, either-- though I rarely used many of the switches on the Ecstasy after I found "my" sound on the amp (though other might like the freedoms those switches all allow).
Slo is voiced brighter than the Ecstasy, so that's a big difference-- probably the biggest difference, in my opinion. Do you like dark, organic, and lots of harmonics (Ecstasy) or do you like brighter and even more harmonics (SLO)? But, that being said, the SLO is still plenty versatile, drips with harmonics, sounds great no matter how you set it (on all channels, IMHO), and will hit you like a freight train when you hear it. The Ecstasy and SLO are the two amps I've heard that have honestly stuck out and blown me away.