Not an easy answer. I generally like chain maker's tongs with the V shaped jaws. They can hold both round and flat work. For heat treating I like wolf jaw tongs. I also have a couple of blade tongs that have the ends of the blades bent over to hold flat bar but I'm absolutely blanking on the name. The maker has relocated to Taiwan, if anyone out there can help with the name. Get tongs with the longer reins, that's to say handles. The longer the reins the farther away your hands will be form the fire. They will spread wider but you can always adjust them a bit before you start forging. Still a couple of jaw widths are nice to have. If you are anything like the rest of us you will be developing a collection.
Hammers are much the same. Cutler's/saw maker's/Japanese hammers, where the eye is set to one end of the head, are nice but may be a little harder to control than "regular" types but be more effecient. Different face shapes will move the steel slightly differently. All but one of my hammers are square or oblong in the face. Sometimes when I need a round faced hammer, I need a round faced hammer. It will move steel equally in all directions. Square faced hammers will move steel equally top and bottom and side to side. Oblong faced hammers will move steel the most at right angles to the long axis of the face. My hammers also have a very slight crown to to face, except for the rounding hammer, the one with the round face, which has one face that has a rather domed face. It really moves the steel in all directions but it will also leave a lot of dimples in the steel that will have to be flattened. It's a bit of knowing what to use and when. All but one of my hammers are smithing hammers. One, with the long axis of it's face at a right angle to the handle, was reforged from a 2lb ball peen hammer.
Most of my hammers are in the 2-3lb range with 2-2 1/2lb getting the most use. The three pound hammer will really move the steel and it works in combination with my flatter, spring fuller, or guillotine tool but I still tire more quickly using it. It's not so much that I can't swing it for long, it's that I can't swing it for all that long with control. I have a 1/2 kilo hammer that I use for fine tuning where I want more to bend and flatten work than to move steel. Then I have a 4lb hammer that I only use to stamp my maker's mark with. I even have a wooden maul, aka a thwacker or thwocker, that I use to bend and straighten where I really don't want to compress the steel.
Doug