I use a discone with a TV preamp, it works well enough, but your mileage may vary (as with anything). LMR or Heliax is going to give you the least loss but it's expensive and probably overkill, my discone is fed with LMR240 but I only went with that because I have a fairly long cable run. If all you're after is low band you'd be good with RG8X, loss at 30MHz is less than half an S unit per 100 feet and it's pretty inexpensive as far as coax goes. Obviously, keep cable runs as short as possible to minimize loss. Also get the antenna as high as possible and play with different locations: the antenna may be dead in one spot but a foot to the left can hear everything.