The Rivera is the most flexible but has the least individual character to its tone IMO, and is possibly the best built. It's also the largest, heaviest and loudest.
The Mesa is the least well built (though still very good), has a very particular 'Mesa' midrange character that you'll either love or hate, and is in the middle for volume, flexibility, size and weight.
The Super Champ is also very well built, is tiny and very portable, but is the least flexible, the quietest and with the smallest sound - the almost complete lack of bass when pushed isn't always a disadvantage though, it can work in a mix extremely well.
If I could only have one as my main amp I would pick the Rivera. It simply covers more ground and more situations than the other two.
If I had one as a second, small amp for grab-and-go-situations I would pick one of the other two depending on which tone I liked the best.
If it matters, I actually did use Super Champs as my main amps for quite a while (two were necessary to get enough stage volume in many places), but that was in six-piece pop band where I needed to occupy a fairly narrow space in the mix and the naturally bright tone was a good thing. As soon as I moved to a band where I needed a fuller guitar sound they didn't really work at all. I kept one for a long time afterwards and occasionally used it for gigs where I needed more of a personal monitor than an 'amp'.
I also used a Subway Rocket Reverb for a while with a band, and I liked it but I'm not sure I would want to use one as my main amp (and I do like Mesa amps, a lot). I never played live with the Rivera but there was one in a shop I worked for for ages - it was always my go-to amp for demo'ing guitars because I could get a good tone with anything and in more or less any style.
Impossible to answer out of context, but the overdriven sounds on the Mesa are much, much nicer than the Super Champ, (The drive channel on the Fender is essentially useless) The cleans on the SC are much nicer than the Fender. The Rivera will probably split the difference, so for versatility that is your answer.