If you are going to be Spread-Betting then you want shares that show Volatility.
You can see this very well by looking at Candlestick charts. Just look at the size of the candles !
Also think about the time span you plan to trade - are you day trading or swing trading over a longer period ?
Some people are happy range trading using channels or Bollinger Bands - again look at the charts and you will find shares that show quite distinctive Support and Resistance levels - with the price 'ranging' between the two . Beware that eventually prices will break out and a new range will be created.
Poor you, you seem to have a long list rather than a short one! Another thing I look at is the actual price of the share. I know what risks I am prepared to take with my account. For example I will take a 3% risk with my FOFLS trades because I know the system. For "hunches" I would only take a 1% risk. That to a certain extent makes some of the higher priced shares (although there are fewer of those about now) out of my price range to trade because I couldn't place the stop in my risk tolerance area.
Just another factor to throw in to the general confusion.