Which would hit "harder"?
It's after 1am, I'm wide awake and feeling "wordy"... so bear with me.
It's not really a dead nuts relevant question - in that opposing magnets are,
with a few exceptions, used as a substitute for a spring - on the
button side of the button collet tube and have nothing to do with actual battery contact.
Upside to magnets are that they don't wear down or out and can be infinity "tuned" for resistance by adding, subtracting or varying thickness and strength.
Upside to springs, easier to find and/or make, can be infinitely tuned (stretched, cut, heated to reduce tension, changed etc etc) same as magnets and at present, are generally way cheaper at the retail level.
Magnets of a specific size to fit 'X' mech mod can be difficult to find (ask me how I know
) as most (seem to) come from China and Australia. eBay and "SuperMagnetMan", along with Apex and KJ magnetics can be good resources if you want to find "ring" magnets of a specific ID/OD/thickness. Also, Dennis at Fat Daddy Vapes carries some ring magnets for Sigelei, Chi you and Ba gua.
Mechs like the
Madz Modz Nzonic are the exception. They are OE with permanently inset magnets and use an "intermediate" contact between battery and firing button. Although the Nzonic (and clones...
ehpro being, the best) is easily one of the most popular mechs ever, the design adds a bit of length to the mech... about 3/8"-1/2". Intermediary contact not withstanding, the Nzonic (and ehpro clone) both have very minimal voltage drop under load.
I like magnetic buttons, but I won't buy a mech just because it has a mag button... quality of contacts, voltage drop, thread quality, fit and finish are more valuable to me, IMO.
If "hit harder" is your number one feature...
look here.