They all have their good and bad points
I spent a very happy 12 years flying from Nottingham but have since moved house and haven’t flown from there for the past three years – so things may have changed. There are (were) two fixed wing schools – Sherwood Flying Club and Truman Aviation. Sherwood is a flying club in its own premises, run on an amateur basis by retired professional pilots and volunteers. Truman, which until recently also used to own the rights to the airfield is a flying school with paid instructors. However, both clubs organise events such as fly-ins, barbecues, trips abroad etc. Both as far as I could tell had high standards and I took refreshers, revalidations etc with both clubs and had no complaints. The atmosphere at both Leicester and Nottingham is very different but I would not like to say which is better. There used to be no food at Nottingham except at weekends (may have changed recently as the new owners are thinking ambitiously) whereas Leicester has a licensed facility and we used to go there for lunch. Leicester is bigger, a better choice of runways and a more interesting mix of planes on the field. If it does not matter to you which to choose from the point of view of convenience of access, then I suggest you visit them both on a Saturday morning and speak to a few folk. I have always found I got as much enjoyment from a club environment and shooting the breeze with fellow members (some of whom are extremely experienced) as actually committing aviation.
One thing to bear in mind if you are also considering East Midlands. I originally took my PPL at an international airport and although I learned air traffic procedures and was comfortable being able to mix it with the big boys, I spent hours at the hold or in downwind orbits. However at Nottingham Air Ground, you are on your own, which teaches decision making. As for landings practice, I could easily get in at least 6 landings an hour at Nottingham with tight circuits and very little traffic whereas where I learned I was lucky to get in three landings per hour and my circuits were necessarily of the cross country variety. And If the Nottingham circuit is empty you are permitted to do glide approaches to the runway from the overhead which is amazingly valuable as PFL practice.
{Please bear in mind that all my comments reflect my experience as of three years ago – more recent members may have corrections.]