hard to say without using gut instinct whilst viewing!
speak to other parents first?
obviously organised, well qualified staff, cleanliness, nutritious food and no 'nappy aroma' is a good start BUT messy with toys and walls crowded with children's creations is also good!
my grandson has 'auditioned' three places, and he ended up at one full days until he started school! now he goes there for a holiday club BUT they couldn't collect from school, so he goes to another after school only!
i would say the one we first chose has slightly better equipment, decor/light/space, facilities, staff/management and ethos, than the other, but both seem popular ...
i have done my own lightening inspections when 'dropping off a forgotten hat' or whatever and have never caught them napping!
make sure you put your name down as asoon as possible as they get really booked up! and expect to feel funny for a while when leaving him/her!
i would be especially put off by staff smoking outside and unsafe parking/drop offs!
cath x