Civ4 AI strategy

I find it strange that the AI see's such importance in getting Scientific
Method / Communism & Physics.
Myself, I beeline for Railroads and Corporation then get Mining inc. and
then move on to Assembly Line for Infantry.

In recent wars I'm hit by airships enroute to take enemy towns but when I
get there my canons and infantry meet longbowmen, ocassionally riflemen.
Provided I have someone in the stack with the medic promotion to repair
airship damage to troops, the battle is soon won.

Yes, I may loose out on a great spy / great scientist missing being 1st to
get Communism / Physics but the high productivity of cities with mining inc
& factories churning out infantry at 1 per turn seems to have the edge.

What way do you go?