i agree with ill clyde
aluminum is probably better
but the difference will be small

i recommend getting a sport touring style bike
or a cx or touring
that can handle slightly wider tires
and probably has lower gearing

23mm wide tires under a 300+ pound rider is pointless
like carrying construction waste to the dump in your ferarri
good 28 or 32mm tires roll lightning fast
and dont have to be pumped to 160 psi to hold you up
which causes discomfort and loss of efficiency