I suggest a middle of the road approach. Of course, different choirs have varying criteria for choosing music. On ChoralNet I asked just such a question in a forum and got some amazingly astute and helpful answers. Before we can even begin that process, I think there are some really important criteria we must meet.
1. What kind of choir are you? A chamber choir or church choir will choose much different music than a community choir. Do you sing for a paid audience or just for community events? In our case, we have chosen not to have set concerts so we can sing an eclectic group of songs that might not work in a concert situation. Before even looking at music, you have to know WHO you are.
2. What voices do you have? Having worked with changing voices for much of my career, the music I chose had to be comfortable for all to sing whether their voices cracked or not.
Now we have adults who can pretty much count on the voices to stay the same. They love to sing in 4 parts and we have strong singers in each so we choose music accordingly.
If you have girls voices or women only you won't be singing songs of the sea for instance. The pieces must be shown off by the voices you have in the style that works for your choir.
3. How many are you? Our choir is not large, just around 20 voices. We must not try and do "Battle Hymn of the Republic" as it would sound reedy and ineffective. We need to focus on pieces that depend on finesse and acuity I think. What a larger choir can do is not always effective for a smaller group. In a larger group, if someone makes a mistake it is often "drowned" out by the sheer numbers of other singers. Not so with fewer singers. Those inaccurate sounds stick out. Choose songs that the singers feel comfortable singing otherwise their tension will spoil the sound.
4. How much time do you have? I was amazed to find out that some choirs practice as much as 12 hours the week before a concert. Our choir only meets every second week so we choose music that we can do well in short bursts. Sometimes we add extra practice time but one reason people joined our choir was that it wasn't a weekly commitment. We will never do the whole of the Messiah. If you choose music that is very tricky and you only have a short time to work on it then you are just asking for trouble.
I know some choirs are paid and must attend a specific amount of time. I am not referring at all to those situations. Volunteers need to have their time and TALENT respected. Choose carefully.
5.. What do you love? Our Embro Thistle Singers amaze me always. Our last rehearsal was delicious. They were sensitive to dynamics, words and harmony. Each part was aware of what they needed to do and knew when to ask for some help. At the end, although we have never formally worked on "For the Beauty of the Earth" by John Rutter, we do have the music and they couldn't leave until they had sung it. They simply love that piece and it is dessert at the end of a fine meal. How cool is that? Do they love all the pieces we do equally? No, not even close. But enough love each one so that each comes off well. They are willing to sing their less favourites in order to be able to sing the others. Our job as directors is to find those pieces that work for our singers and our public presentations.
When we find a piece that really doesn't hit any buttons, no matter how fine or fun it is, we drop it. It is that simple. Unless you are singing set pieces for a festival or competition then why work hard on what doesn't stir your passion. Yes, I have taught 14 year olds to sing, "A Misty, Moisty Morning" and it wasn't easy. But we also sang "Good Morning Starshine".
If they don't enjoy singing the music, the performance will suffer. Does it mean you have to "dumb down" and use extra simple music. No. Just choose to suit your situation. What do you do?