I don't bother with armor of any kind. I prefer to stay mobile, but I always add on the leg charger, and cooling system if I can get the ender pearls. If you've got the cooling system, you can put on the high power solar array. I have to carry two helmets if I'm working in a desert though. I don't necessarily use a jet pack. Flight feels... over limiting. Instead I use a Tinker's Longsword, the legs, and glider wings. It's energy free and you get a long distance of flight out of it.
I used to use step assist, but I don't any more. Too many times I'd hit the button and take a flight I didn't intend.
For the power tool, I prefer the saw blade launcher to the rail gun. Add shears, a grafter, and a maxed out Rototiller. One click does a maxed out farm as far as I can tell.