What kind of amp do you have? This will alter the recommendations quite drastically. If it's a standard Marshall type then it more than likely uses EL34s. JJ EL34s are considered pretty decent for a good rock sound. I think Fenders usually use 6L6 valves... but I'm a Marshall guy so I could be wrong. I usually buy my valves from Hot Rox UK - Computer Matched Valves Guitar effects pedals Electro harmonix Guitar Strings as they're generally considered better than Watford Valves :: Watford valves is a U.K company that has become one of Europe's leading supliers of tested, graded and guaranteed valves to the professional music industry. - but I've never had any problems with Watford Valves.