After the era of the well known Thai Bhikkhus like Ajahn Mun, Ajahn Tate, Ajahn Maha Boowa, Ajahn Waen and Ajahn Chah; Which Ajahns are considered as Arahants or Highly developed Meditators,in these days? (I'm asking this not to arouse curiosity of others, but to find good monks' Dhamma talks).
I'm asking this not to arouse curiosity of others, but to find good monks' Dhamma talks
An accomplished practitioner may not be a good teacher and a good teacher may not be an accomplished practitioner. In some cases teachers maybe both.
So ideally you should look for teachers who teach well, both theory and mediation.
Also the Buddhist should follow: pariyatti (theory), patipatti (practice), pativedha (experience). Whereas learning / listening to the Dhamma is just the 1st of these 3 parts. So a person should teach the theory he should teach the practice also well. Theory without practice is like an unused boat. You should row (patice) the boat (theory or tool) to get to see the other show (experience).
Also accomplished masters may not say so and also some who are not accomplished may claim to be so. Hence it is best not to look at this aspect in deciding who to listen to. Also see if the teaching sounds right, is logical and put it into practice and see if it is beneficial.
As always go to the source. The Tipitaka a the primary source and commentaries and sub commentaries as secondary and tertiary sources.
Only a Buddha can truly identify an Arhat, so beware of people who take up robes declaring they are stream winners and teach their own wisdom instead of the current teacher of Buddha and Buddhism: Dhamma.
Now there are translations of the original Dhamma and they are easy to understand. Using these sources will help you clarify your doubts.
There are priests who preach direct translations of the original Dhamma. Please find one of them for your guidance.
In Udana 7.2, Ven. Sariputta (the Arahant) tried to teach Ven. Bhaddiya without realizing that he too was an Arahant.
The Buddha saw this and remarked, describing Ven. Bhaddiya:
He has cut the cycle, has gone away to freedom from longing. The dried-up stream no longer flows. The cycle, cut, no longer turns. This, just this, is the end of stress.
This shows that the Buddha could recognize who is an Arahant, but not another Arahant.
So, basically nobody could definitively identify an Arahant today.
The other thing is that monks are not supposed to disclose their spiritual achievements to lay people, according to the Vinaya. Even if they did, you can't verify it.
It's not hard to verify that someone is not an Arahant, but it's impossible to verify that someone is definitely an Arahant.
In reading the Ariyapariyesana Sutta: The Noble Search – MN 26 one come across the group of five monks (Kondanna, Bhaddiya, Vappa, Mahanama and Assaji) who attended to Buddha when He was resolute in exertion, before Buddhahood. They were far more intelligent than any of us in the present day. Even they could not identify the Buddha as an Arahant. So what would make one think that a present day monk can identify an Arahant? Only after a monk leaves this existence can one identify that he is someone special (an Arahant ) in observing the dead body. Such an incident took place in Sri Lanka, a couple of months ago.