I got the 7 watt Goal Zero panels for recharging a few devices while I travel around in my Prius over 2 years ago. I find it works ok for charging my smart phone, wifi hotspot, and recharging batteries. It takes more than a day to recharge a drained battery on my tablet/laptop (2-in-1 type).
I liked the smallness and convenience of the panel, but knew I wanted more wattage. So, I got 2 more folding panels -- Renogy 14 watt -- for a total of 35 watts altogether. This has been working well for me now for over a year.
The thing I like about the Goal Zero product over Renogy's, is the additional types of plugs, in addition to USB. But, I like the extra wattage and cheaper price of the Renogy panels.
Hope that information helps in your decision making.
Suanne