Hi Gerry,
Tom's correct regarding the Technics machines. The 1700 is the only one that is 1/4 track only and they command some pretty steep prices also (they're rather rare and sought after by collectors compared to the 1500,1506 (which differs in it being a 1/4 track recording machine rather than 1/2 track recording like the 1500,1520).
The Otari's are an excellent choice and given the current used market, are a flat out bargain for the machine you get. All of the 5050bll series have 1/2 track and 1/4 track playback facilities with the exception of the later mk4 model on which the 1/4 track playback was an option (it's a good idea to ask the seller if it has 3 or 4 heads just to be sure an earlier model hasn't been modified). It has switchable NAB/IEC equalization (you need IEC to playback the Tape Project tapes properly) and is a very solid machine.
In regards to machine position, some folks have experienced some problems with using the Technics machines laying flat but that's something that may be a matter of adjustments.
The Otari's did come in models that were designed to be laid flat but if you were to change your mind somewhere down the line, you wouldn't be able to stand one up without some major modifications. You could do what a number of the members here do and mount the machine on a stand that tilts the machine back (with just about any machine actually). Larry Toy has a couple of stands which were made for guitar amps which are very nice for the money and look fantastic in his system.
BTW,.. you can't play 1/4 track tapes on a 1/2 track machine. The two "flip side" channels will be reproduced backwards.