I encourage those considering these schools to read the Fiske Guide to Colleges. Lots of great info. Seems especially high on Southwestern for undergraduate research, small classes, and one-on-one counseling.
OP: If you have done your own research & are comfortable with your findings/thought/conclusions than that should lead you to the school which is the better fit for you & your interests.
P.S. Fiske points out the tremendous wealth of Trinity University & how that wealth benefits students.