Use a trimmer first then a razor with a flexible head. Save in the direction of the beast bone (manubrium). If you wax it'll take awhile but the maintenence will be less often. Dont use a trimmer if you decide to wax. That makes it more efficient. If you shave you'll get immediate results but have to do maintenance about every 3 days. The advantage to shaving is that if you decide to grow your chest air again it won't take as long. I'm a physique competitor so I shave because waxing left red bumps but they go away. It just depends on whether you can wait long-term.
i think waxing or trimming is best. it really depends on how much hair u want. i dont mind hair or no hair so I'm not picky with this kinda thing. but do NOT shave. it'll end up looking and feeling like ur facial hair. that spiky ish ain't cool