Almost all of the literature and advice about teaching kids says you shouldn't play favourites... and I think that's wrong!
I mostly 'play favorites' because I only see my students once a week, but I do it for other reasons, too. It's a balancing act... I sometimes favour the enthusiastic kids, because I think they'll enjoy the class more and benefit from my extra attention in the long run. I sometimes favour the restless kids at the back, because I think that sometimes, a jolt of attention might flip a switch that makes them keener and more attentive to learn.
I favour girls more than boys when the class becomes restless... because if the girls are talking when they shouldn't be, there's a good chance it's about what 'I' am doing. If the boys are chatting out of turn it's probably because of what 'THEY' are doing!
In Thailand, most large (40+) classes are overloaded with under-performers. When your time is at a premium you have to share it judiciously among the crowd. So you have to make hard choices. Students also have different 'roles' to play which can help you to be a better teacher. Some kids will lead the chorus and some will mouth the words that they don't know!
Like I say, it's a balancing act. Some of the quiet kids can surprise you with how much they've actually listened to and retained, so I try not to overlook these kids... which is hard to do, because the quiet kids are almost invisible to the teacher. Asking questions to kids who you know will answer correctly the first time can often help the unsure kids to raise their hands, because they've seen it done and that's how they would have answered... so they think, why not have a go. There's also a lot of in-class 'mentoring' going on where kids feed each other the answers. I used to find this exasperating, but I've learned that, actually, this can be an awesome tool, if it's managed correctly.
In an industry where we are mostly under-paid, under-appreciated, give yourself a good slap on the back for going against the grain and doing things YOUR way!