Depends completely on your goals and the style of workouts your doing. For example, I'm currently training in a bodybuilder style fashion with lots of volume and hitting sets of between 10-20 reps, therefore a pre-workout which accelerates the pump is necessary. A little caffeine but nothing too crazy, I'm not doing any max heart rate HIIT cardio but a nice serving 150-200mg of caffeine is a sufficient amount to get my head in gear ready to lift. I'm not looking to lose weight so I'm not too concerned about a pre-workout with ingredients that promote thermo genic responses (e.g green tea extract) but these don't hurt to take to keep the metabolism fired up. If fat loss is more of a priority for you then you'd want a pre-workout like Grenade, if you're more interested and focused in building muscle and achieving a 'pump' then NO-Xplode or SuperPump Max are your ones. I actually haven't tried many pre-workouts as I like to stick with what I know works which is the three I have mentioned, however I may have to check some of the others out on the market soon.