Hello, I am a piano student who wishes to study at conservatoire next year.

As I am very fond of Mozart sonatas and they are very academic as well, i decided to buy myself the whole Mozart sonatas.

The editions I've searched so far are:

ABRSM edition

Barenreiter edition

Henle Verlag

I personally learnt until now with ABRSM edition and found them quite helpful in places.

I'm thinking of Barenreiter edition.

Does anyone have any recommendation on any of these editions or any other publishers please?

I have (have had for a very long time) volume 1 of the ABRSM edition and Volume 2 of the Peters edition (and one sonata missing in the gap in-between!). I recently got the Henle Verlag edition and find it much better than either the ABRSM or the Peters.

The fingerings are very good. Both ABRSM and Peters are generally OK, but very silly and difficult in places.
Ornamentation is more accurate/authentic
The paper, layout and print quality are a class better, and this makes them easier to read and use (and a pleasure to use)

I think they are probably more definitive.

I don't know the Barenreiter.

I have had at least three editions over the years. Henle Verlag is the best.
Note that not all editions include K570.

The Barenreiter is safe, but it may be an Urtext, in which case you would have to work out your own fingerings. Another possibility would be to buy the miniature score of the sonatas in the Barenreiter complete Mozart edition, and use it as a check on a full-size performing edition. The complete set of miniatures cost 300 pounds sterling in the early 90s introductory offer and has 20 volumes, so each at an average of 15 pounds sterling then, presumably considerably more now. However, in one volume (over 1200 pages) you get all his solo, duet and two piano pieces, not just the sonatas; also works for organ and mechanical organ (Orgelwalze).

The Henle-Verlag claims to be an Urtext - but it still has fingerings (very good ones)

I have book II of the above Henle-Verleg, and agree the fingering is very good. That would be my two penneth worth!

I don't have any of the editions, but found a resource that might give you an idea of what the Baerenreiter editions might look like, since most of the scores come from Baerenreiter:

Digital Mozart
http://dme.mozarteum.at/DME/nma/nmapub_srch.php?l=2