I have 3 seats in my Pilot. All 3 are in the center row, and only one of them has LATCH. I have my son's Marathon installed with LATCH. My baby's Roundabout is installed rear facing in the center with the seatbelt, and my daughter's Freeway is installed outboard with the seatbelt.
Assuming a good fit, I'd install the seat in the center with "just" the seatbelt as my first choice. This puts the child farthest from a side impact, and is generally the safest place to install a seat. If I had to put it outboard, I'd try to install it with LATCH first. If it fits well that way, great. If not, then I'd try the seatbelt. I can install my Marathon slightly faster with LATCH than with the seatbelt. A good install is the most important factor.
One final note, you didn't mention what kind of seat you are installing, but I did find that I cannot install the Britax Roundabout in the rearmost seat on the passenger side. It is incompatible. It has fit in all the other seating positions, though.