love all the posts recommendations for quarter mile cars when an enduro might be needed .... anyway
from a theoretical point your square room is probably the lesser sounding of the two but the odd shaped ceiling will most likely help a bit. The other larger room with high ceiling and openings will most likely sound better. Will they be furnished with living furniture, etc or the audiophile sterile dedicated room aesthetic?
i will check my Texas network for ideas on reputable dealers.
do you have much vinyl? What service do you use to stream ? Do you have any CD or SACD ?
have fun