Yes for the time being Hl Enhanced is the best option. My coder and I are still waiting for the moment it is entirely finished before we continue on our work of Half-Life Opposing Force SDK.
https://github.com/Hammermaps-DEV/SOHL-V1.0-RefreshIt's a somewhat outdated version but still rather epic as it contains some of the best monster op4 recreations I've seen to date. Only Svencoop managed the same quality of recreation. The thing here is that the coder managed to access the files and values of the original op4 entities and just duplicated em. So they behave almost exactly as the Op4 monsters in Opposing Force.
Once Hl Enhanced is completed we will release an enhanced version of Op4 based not just upon the Op4 entities but about everything the community came up with over the years as well as own additions be it female scientists (models already present based upon cross&green in scientist coats.) and so on.