The type of antenna you need is TOTALLY dependent on where you live.
TV is broadcast on 3 different RF frequency bands, VHF low (real channels 2-6), VHF high (real channels 7-13) and UHF (real channels 14-52ish). I say real channels because digital TV introduced virtual channels to TVLAND, so you have to do some research.
Each band requires a slightly different length of antenna element so job 1 is to find out which stations you want to receive, then determine what the ACTUAL broadcast frequency.
www.TVFool.com is probably the best source for what you can receive and what frequencies those stations actually broadcast on.
Here is my TVFool report @ 25 ft AGL (above ground level):
http://www.tvfool.com/?option=com_wrapper&Itemid=29&q=id=e2cbfac29db3de
You will see that my real channels have a channels 6 and a channel 11 and a channel 13 listed in the VHF range and all the rest that are receivable are UHF - NOTE: I consider only channels with a NM(dB) in the positive range as receivable, however it has been known that reception down to the -10 area can happen.
So, if I want to receive all the available stations, I need either an all channel combo antenna or some combination of antennas that can receive all three bands. I really don't care about channel 6 so I use a VHF-high/UHF combo antenna.
The second consideration is how strong are your signals?
Once again we go to the TVFool Report. If your wanted channels are in the green, you can probably get all of them with a small outdoor antenna ( never recommend an indoor antenna unless outdoor is impossible).
Even in my strong signal area (NMdB above 35) I use an antenna larger than necessary because I split the signal to multiple TVs and every split cuts signal in half and without any amplification overload is not a worry.
If your signals are moderate, you need a larger (more elements) antenna to get a proper signal.
If your signals are very weak - fringe - you need a very large antenna and may need a pre-amp to get stable reception. Yes, yes they say a pre amp is only to overcome line loss, but a good quality pre-amp with a low noise level can actually pull in otherwise unreceivable signals in extreme cases.
Once you have decided on your antenna, then you need to place it as near to the TV as possible to avoid line loss (RG-6 75ohm cable has a loss of about 3dB per 100' that's 1/2 of the signal), so short cable is preferable.
If your signals are in all different directions, that's another problem, especially in weak signal areas - another story for another time.