The TCe Corona (larger version no the mini) has the tone print option which makes it very customisable, plus there is some software available to tweek and twiddle. I had one for many years and I only recently dropped for a Strymon Mobius. I love the CE-2 tone print and the fact that it is stereo capable too. I like the clarity of the chorus and that it can sit in a mix and add a subtle sizzle without dominating but still be heard. It can do the heavy chorus too but I liked the more subtle stuff. The MXR is a slightly different beast. There are no options other than it's baked in sounds but they do sound good. It's more of a modern sounding variant on a classic Chorus sound and it's got the option of the flanger. I like the Xover function for effecting only the trebles and mids (sadly missed on the TCe unit) and I like the bass and treble controls, that's a sweet feature. It's also an analogue chorus so it sounds a bit fatter and punchier than the TCe.
Neither are better, just different and tailored differently. So there's no wrong choice here, just personal taste. It would be wise to demo both but no harm in taking a blind plunge either.