bakhurts

Guys, I am just getting back into cycling. I want to ride about 1-1.5 k per year, not race. I'll do a couple of charity rides. I tried both bikes in a parking lot, and can't decide. i will get around to trying to borrow or rent these bikes for a longer ride, but so far it is a wash. i would appreciate any information or opinions, realizing these are subjective.

i'm not young, and my bak hurts, specially when i try and go too aero. any other ideas or bikes??

thanks
bh