The #85 EO liner lock is a worthy consideration. As previously mentioned the#72 & #42 models open very easily and are lockbacks. A new run of #72's is being run soon in different blade shapes and handles which can be preordered through dealers. A few #42's can still be found. The BullLocks have a strong backspring and the lock takes some effort to release as well. For ease of operation I lean to the #42/#72 models.
"Sharp blades are good to have, if Shire-folk go walking, east, south, or far away into dark and danger" - J.R.R. Tolkien