As you may have gathered asking this question in other forums / FB posts, it's a loaded question that contains a lot of emotional reactions, bias, and of course subjectivity. My own biases are towards Hammond Suzuki, since I'm an artist with them but I will preface that by saying that I approached them, not the other way around. And as of this writing, they have not given me any digital organ for free; I paid for my XK System that I used with organissimo and others from 2008 to 2012 and I paid for my SK2 that I use now, albeit a discounted price.
With that out of the way, I have played all the models you're considering with the exception of the KeyB Legend.
I currently have a student that owns a Mojo, so I play it several times a month during our lessons. Before I give my impressions, note that I have owned and used the VB3 software for going on 10 years. I still use it in some of my work today though usually it gets replaced by either a real tonewheel console or the Hammond SK1 / XK1c.
Concerning the Mojo, the short version is that I am not impressed by it. I think it sounds overly processed, the bass is rather flabby and ill-defined, and it has a strange latency that I can't believe other Mojo users don't notice. I honestly do not understand why it is as venerated as it is among organ enthusiasts. When I play it, I feel like I'm playing a synthesizer's idea of what a Hammond should sound like. I don't know if that makes sense. I think the chorus/vibrato is very good, the percussion is good, and the Leslie sim is good, but the overall tone and especially the latency or maybe better put the feeling of disconnect between my fingers and the sound really bothers me.
I will say this: Whenever I use VB3 to demo a song, when I replace it with either the real deal or the SK / XK1c, the replacement fits so much better in the mix.
The XK5 is a different beast altogether. It is way beyond the XK3c, which is a great board. If you are an organist, if you have any familiarity with the real console tonewheel Hammonds and how they feel, then you will understand why the multi-contact system in the XK5 is so important. If you've never played a real Hammond, then you might not understand.
I really think the XK5 is the best Hammond emulation on the market. But yes, it's expensive. And big.
The KeyB Legend sounds really nice but I think those two videos from NAMM that show Cory Henry playing both the XK5 and the KeyB Legend speak volumes. The Hammond responds like a Hammond should and you can hear it in his playing and how he plays it. The KeyB sounds nice but it doesn't respond like a real tonewheel organ and for guys like Cory that literally grew up at the console, that's a big deal. Playing a clonewheel changes the way you play. It's the same for an acoustic piano vs a digital piano. You have to play a digital piano differently than a real acoustic. Same for a clavinet. It's REALLY easy to emulate the sound of a clavinet yet nothing emulates the actual feel of playing one. And once you play a real one, you understand why it is played the way it is; why Stevie Wonder came up with those funky clavinet lines on Superstition and other tunes. The actual feel of the keyboard makes you play a certain way.
I'm still happy with my SK2. It sounds great. The XK5 is far superior though and there are moments in playing the SK2 where I try to pull off a technique that would sound so great on a real Hammond or on the XK5 and it just doesn't work. Case in point is this video. The sound, I think you'll agree, is killer. But dig when I do the glissando up to the high C during my solo at about 2:14 or so, it just doesn't sound authentic. This is because of how the SK2 and every other clone except the XK5 triggers the notes. On a real Hammond, doing a fast glissando like that would mean that not all the contacts under the keys would necessarily close nor would they close at the same time, making the sound almost like a 'wah wah' effect as you glide up. In other words, it would be more organic, less perfect, less stiff.
So it boils down to two things: 1) What is your budget and 2) Is authenticity more important than weight / cost?
Hope that helps.