The present continuous emphasizes action in real time.
For example, an announcement is made repeatedly over the train-station loud speaker:
The [garbled] will be approximately [garbled] minutes late due to [garbled].
The [garbled] will be approximately [garbled] minutes late due to [garbled].
A passenger waiting in the station could turn to another and ask:
What is he saying?
P.S.
The implication is that speaker and listener are in a situation where this announcement might be made yet another time. The present continuous refers to it as something which is ongoing or repeating.
If the speaker believed that the announcement is not likely to be made again, or is perceiving the announcement as something that took place a moment ago, the question would probably be:
What did he say?
In this particular contextual example, the question would not be asked in the simple present:
unidiomatic What does he say?
unless it referred to a specific place in the announcement:
What does he say after "due to"?
What is he saying after "due to"?
The answer could be, respectively:
He says "due to switching problems".
He is saying "due to switching problems".
The simple present there would refer to the phrase that follows "due to" in the announcement as one that occurs with some predictability or regularity: he says it in the same way each time he says it.
The continuous would refer to the phrase that follows "due to" in the announcement as one that we are hearing him say again and again.
P.P.S.
Even if the announcement comes over the loud-speaker once:
[garbled] [garbled] [garbled] [garbled] emergency [garbled] [garbled] [garbled]
a person might turn to a fellow passenger, even as the announcement is continuing, and ask:
Can you understand what he is saying?
The announcement is in progress.
Both are correct
The present shows that you recommend something, and you may do it multiple times:
I recommend this to my customers.
I recommend that you use this.
The present continuous suggests that you recommend something at the time of speaking:
I am recommending this to my customers.
I'm recommending that you use this.
Both of these show that you are actively recommending something right now instead of in general.
Best Answer
Often people desire what they lack, and in the context of this sentence, these phrases mean the same thing.
However, there are other contexts where lacking something doesn't imply it is desired.
Is a sentence where the lack of knowledge and the desire of knowledge are not aligned.