which is better ? MC phono stage or MM+step-up ?

Yes, there are many ways leading to Rome.
I've walked them all in the past 30 years.
However - there is only one Via Appia leading direct to the Capitol hill (not Washington DC, but ancient Rome, Italia ...) and the Forum Romanum.
You do bring a JFet hybrid phono input stage to superb results. Certainly enough to meet the quality of most any phono stage available on the market in the ears and eyes of most audiophiles and all reviewers.
But the very best phono stages aren't available commercially.
And they can do without the anabolica of JFet-tails.

Let me put one thing straight here from my point of view: it is not about SUT vs high gain phono stage.
These are not competitors in the race for phono gain.
A - precisely matched !! - step-up transformer should be viewed at as one half of the LOMC. Both devices do ask for the other. This is all about matching technical parameters depending on each other.
And doing so to bring out the optimum performance parameters - not because of gain, but because the right SUT provides the optimum working conditions for a LOMC.
And yes, - most LOMCs will work in a high-gain phono stage w/o SUT too. Most good phono stages do provide selectable impedance settings to further accommodate the LOMC. But they can't provide a matching inductance and I think this small factor is sadly neglected in most discussions about phono gain/LOMCs.

This is a very interesting thread. My situation was that a well-regarded, but still relatively modestly priced phono stage with a JFET had been heavily modded. Even then, that left a modestly priced JFET still in the mix. The EAR MC-4 is a flexible, well-built and well-regarded unit. It is is nice complement to my modded phono stage run in MM mode. And yes, it is not purely about gain. I swapped 20 db of JFET for 20 db of SUT.

The use of JFETs + tube or pure tube or SUT + tube, etc. in a well-designed, top-of-the-heap unit, such as CJ, Atma-Sphere, Einstein, Aesthetix, etc. becomes a matter of design and listening preferences.

I like the previous comment that there are many roads to Rome.

Dertonarm, IME LOMCs have a lot of current. So much that if you short them out completely, the sound from the phono section will only be a few db down (and rolled off on top). Most audiophiles don't seem to realize that in exchange for low output voltage you get high current.

If there is any advantage to using an SUT, it is this fact, although a direct-coupled input stage can take advantage of this as well. I suspect that 20 years from now this will still be a debate, and still largely be dependent on the topology of the phono section.

:-)