You need to consider different things, and then go and look round them and get a 'feel' for what they are like.
so -
Do you need certain days / certain hours ?
In particular do you need 'wrap around care to cover your working hours ?
Do you have a preference for times - do you want 'school hours' or would 8 - 1 or 1 - 6 work better for you?
Are you looking for 2.5 days or for 5 x morning / 5 x afternoon?
If there is a teacher responsible for the Nursery, then the ratio of children: adult is 13:1, whereas if you go to most PVIs (where usually there isn't a teacher present) then your child would benefir from a ratio of 8:1
What 'other costs' might be involved ? Whereas the Gvmnt claims to offer "free" places to children from the term after their 3rd birthday, it doesn't fund the places well enough to actually sustain the place, so a lot of Nurseries have creative ways to collect some of the shortfalls from parents (charging for meals, or childcare over mealtime, or for snacks)
Some Nurseries actually off 'add ons' such as Spanish or Yoga or music, and ask the parents to pay extra for those.
Think of practicalities like how you will get there and back - practically, if your child does a 3 hour session, it doesn't give you a lot of time at home (or wherever you want to be) if it is a 40min walk each way to drop off / pick up. Or, if you have to drive 10 mins away from the direction you need to be doing to get to work (double that in the rush hour).
Then look at things like outside space and access to it.
Some people are quite influenced by the food they serve (or don't - some Nursery children bring packed lunch).
There's no harm in 'asking about' locally - reputation locally is quite a strong indicator.