Like in so many other things in life, there is no one single "best". Otherwise, wouldn't every manufacturer simply make those?
No matter how much I type here, if you want to make an informed decision on what kind of auxiliary lights to get, I'm afraid you'll need to do some reading. And things will get unpleasant right about the time you start to try to pick which lights to buy, as objective comparisons between lights are few and far apart - most recommendations you'll read on the Internet will be more of the "I've always used these and they're the best!" type that don't really say anything useful. Or that at least was my experience when trying to pick a pair of lights for my Jeep.
Wattage is pretty simple though. A watt is a unit of power. Higher wattage light bulb means it consumes more power. Now, how much of that energy is turned into light and how much into heat, that's of course a different story - otherwise things would be way too simple and straightforward, no?
But as a general rule-of-thumb, higher wattage bulbs create more waste heat, so it's not a linear increase in amount of light you get. And that extra heat can cause problems over a longer period of time, such as heating your reflector elements so much they start to become less reflective - resulting in an overall loss of light output. So I would
not recommend defaulting to high wattage bulbs as a standard operating procedure, but rather you need to look at how you intend to use your lights. (Crawling along a dark trail means a whole lot less cooling from air flow over your lights than zooming along a highway at 140km/h.)
In fact, that's my recommendation for you - start by figuring out what you want out of your auxiliary lights. What sort of use are they for, what sort of roads will you be driving on while using them? Do you want to favor longer range, or is the width of the light beam more important to you? That sort of things. Once you narrow it down and have specific questions to ask, people will be able to give you much better answers.
