This is a legitimate concern for many. One does her job, one thinks I'm doing a good job, and only when the layoffs hit or during an annual review is one hit with one's deficiencies.
While I'm not an advocate for meetings, I do think regular one on one meetings between a Supervisor or Manager and her or his Direct Reports is extremely valuable. Here are some questions you might try, but use what works for you and fits you. Over time, it is desired that more natural, instinctive, and casual conversation will ensue during these meetings, but in the beginning you will likely have to take the lead to make it happen.
How are things?
What are the challenges that we aren't addressing?
What concerns do you have about the project, the business unit, etc.?
I see a rare quality in you that you recognize the value in people, both individually and collectively. You are, in my view, correct to be guarded about singling people out for their strengths and accomplishments. In saying, "Bob, you did a great job on Project X", there is this unspoken criticism of everyone else involved in Project X. Most would agree that Bob could not have accomplished Project X all by himself, and there are probably more than a few people who contributed to Project X.
There is a great read, in my view, on this subject called "Peopleware" by Tom DeMarco and Timothy Lister. Pick up a copy, read it, and see if it speaks to you. If it does, buy a copy for everyone on the team and ask them to read it. Go through a couple chapters a week, and meet as a team to discuss it.
Watch "Greatness" on Youtube. It's a presentation by retired US Navy Captain David Marquet. If it speaks to you, show it to your team as a group and elicit their thoughts.