I would add: playing out with a band. To fully evaluate a preamp/drive you need to be in a live setting.Don't try and second guess it. Buy the first one on your list, try it out and return it if unhappy... move onto the next one. Or buy them all on a credit card and have a great big shootout and return what you don't want before the credit card bill comes due. You'll never know before you try them out first hand: your guitar, other pedals, pedal order, amp, playing style and tastes are not the same as everyone else's.