There are many options, and the choices for me were made with consideration of what (and how much) needed to be cut, budget, potential future use of equipment, etc. My tools went hacksaw - borrowed ox/acetylene torch, bandsaw (HF table), bandsaw DeWalt 20V), sawzall, angle grinder, jigsaw (for lighter stuff), plasma cutter.
Nearly everything here is less than 1/2" thick and most is less than 3/8". The plasma cutter is a Hypertherm 30AIR (30A at 240V). It's handy, lightweight and has its own on-board air and runs on 120 or 240.