Single letter generic type params or descriptive with T-prefix?

descriptive.cs

public class LocalEngineClient<TModel> : IEngine<TModel> where TModel : Model
{

  public readonly Engine<TModel> Engine;

  public LocalEngineClient(Engine<TModel> engine)
  {
    Engine = engine;
  }

    public TResult Execute<TResult>(Query<TModel, TResult> query)
    {
        return Engine.Execute(query);
    }

    public void Execute(Command<TModel> command)
    {
        Engine.Execute(command);
    }

    public TResult Execute<TResult>(Command<TModel, TResult> command)
    {
        return Engine.Execute(command);
    }

    public TResult Execute<TResult>(Func<TModel, TResult> query)
    {
        return Engine.Execute(query);
    }
}

single-letter.cs

public class LocalEngineClient<M> : IEngine<M> where M : Model
{

  public readonly Engine<M> Engine;

  public LocalEngineClient(Engine<M> engine)
  {
    Engine = engine;
  }

    public R Execute<R>(Query<M,R> query)
    {
        return Engine.Execute(query);
    }

    public void Execute(Command<M> command)
    {
        Engine.Execute(command);
    }

    public R Execute<R>(Command<M, R> command)
    {
        return Engine.Execute(command);
    }

    public R Execute<R>(Func<M, R> query)
    {
        return Engine.Execute(query);
    }
}