Stick with companies that show you how they did their testing. You must decide WHY you are buying an electronic flash. Then you need a portable unit that is easily set up and taken down. A larger unit with more light output is necessary. Next, decide what type of flash unit you want.
Power packs can accomodate many heads and are relatively easily transportable.
But if the pack fails, there is no light. Monolights are power pack and flash tube combinations. Not as easily transportable, but if one fails, the others still work. Decide what reflectors and attachments you need. Buy units that are daylight balanced and have good modeling lights.