Are there any critical editions of Xenophon that have surpassed Marchant’s OCT? My guess is (it’s merely a guess) that some of the smaller writings of X. like Equitum magister may lack newer editions, but perhaps Anabasis or Institutio Cyri, for instance, have since been reedited?
Timothée, whatever info I have confirms that. A while ago I read a fairly recent (2012) Italian study on X.'s Hiero, and the reference is still Marchant.
The best text of the Memorabilia is the Budé. For the Anabasis it may still be Marchant, though I can’t say for sure. The manuscript situation hasn’t significantly changed, apart from fragmentary ancient manuscripts that show (as usual) that the medieval tradition is less good than has generally been thought. You might check the Budé, but with Xenophon I don’t think it will make much difference what text you use.