I currently have 4 irons and they are all Weller. Like others have posted, bigger tips are the key for big surfaces and you want no less than 60W. When building packs, the hotter you go, the shorter the time you can leave it on the cell/bar.

I have a blue Weller digital ESD station that I use for fine work and always use the fine tip wand. My main iron is another Weller digital ESD station with a bigger tip but ther display konked out. I have one of those 80W Weller stick irons for a backup I keep in my box too.

If I had to buy a new iron right now, the Hakko 936 station is pretty nice.