Why not new posts? That will get you just the content added, not the likes and other stuff. Yes, you will have people's textual posts in addition to images, but those are good to read too, aren't they?
The problem with NEW POSTS is that you have to open each thread to see the content that was added to it.
As far as I am aware - and I’m sure someone will correct me if I am wrong on this - but as far as I am aware LATEST ACTIVITY displays everything that is added to the forum, photographs, comments, and likes. What I like to do is scroll through LATEST ACTIVITY and if I see a photograph that arouses my curiosity I will click on it to see it full size and learn more about it . Likewise with any comments that pique my interest, I will click on the comment to see the comment in full and learn about what is being discussed. By doing this I am able to see and read photographs and comments that have been posted in areas that I don’t normally visit. The downside of this though is that sometimes I have to scroll through several pages of likes between one photograph and the next, and some comments can get lost in the middle of all of the likes. If it is a balanced mix of photographs, comments, and likes it isn’t too bad, unfortunately some members have a penchant for liking every new post in a particular thread - why they feel the need to do that is beyond me, but that is another discussion - and if several members do the same thing at the same time there are pages and pages of likes to scroll through.
If LATEST ACTIVITY cannot be filtered by the user then that is fine, it is what it is.
Focus on Photography is a photography forum, and to me that means that the emphasis should be on the photographs. Surely the excellent photographs that are uploaded to this site should be emblazoned across the site not hidden from view. I cannot understand why this forum does not have a homepage that displays some of the amazing photographs that have been uploaded.
Oh, and just so that you are aware, I also am an ex-POTNer. I joined POTN in 2009 - different username - however, for me FoP is a new start, I don’t believe in trying to hold onto the past.