Hi
We have just been looking at exactly this and our dd started this term.
We only looked at Liverpool College - DH went there - and Merchants. We personally prefered Merchants, as the Preprep at Liverpool was in a not so great building and when we visited, seemed a bit of a muddle. A friend who is a teacher, also visited independently and noticed similar things and that a lot of work was being done on worksheets.
The Prep school however was lovely, light airy, open spaces around it and co-ed. They have had some changes recently, new head and some other stuff, but it all seems to be for the good, however they have started doing IB exams for 6th year, which is I believe a new thing for them and personally, not sure we would go that way, although have a few years to worry about it until that stage! If they had a better preprep (reception - Yr 2), we would probably be there now!
Merchants (Stanfield), has a great Pre-prep and the care the little ones received in Reception was lovely (when we looked around I noticed that they got help in the dinner hall etc), it was accepted that they were still little, not like my dd's old school which just left them to it. We also liked that the girls stay in the same building, so didn't go across to another huge school like Liverpool at Yr 3, so is consistent. However, the boys do go to the boys part of Merchants at this stage.
I am afraid I don't know about the other schools in the area, but so far am happy with our choice, my only little bugbear, is that there is not a lot of grounds/grass around it like Liverpool College.
If you want co-ed then between these two it would be Liverpool College.
Best of luck, it was the most traumatic thing that we have had to go through with our dd to date - choosing a school - (apart from giving birth!). 