It doesn't really matter much...Use whatever is thick enough
to stay up. 14 gauge is plenty. Solid is best overall, but
stranded is easier to work with, and survives kinks much
better. The only reason I call solid best, is I think in some
cases, stranded can cause BC-RFI problems when it gets
real old and starts to corrode.. May be a fluke, but my level
of bc-rfi keeps going up and up every year. This mainly
shows up on 160m receiving in my case...The only
explanation I can come up with is the deterioration of my
stranded antenna wire over time...I've heard of other cases
of this also...But.....Thats a long term deal....Overall, I use
whatever is handy, and 98% of the time, it happens to be
stranded. ..As far as power, it really doesn't matter, except
as far as resistance...You can run a KW into a magnet wire
dipole with no problems. #14 is plenty big enough...I've used
#12 on some antennas, and found it basically overkill...
Even #14 is hard to break and it's a good bit lighter than #12. MK