gondor or rohan its totaly up to what you like my friend
start with an army you like most to see.
i would suggest to add a pack of rangers to your gondor army (if money is the problem consider dropping a hero or two).
if you are a beginer i would suggest focus more on units and captains rather than named heroes (of course buy some tho
) since heroes are a little more difficult to paint you will need to practice and get better on simple untis first and keep the heroes for your finale
so whatever is your choice i would suggest to go with something like that
1 major hero (like eomer or aragorn/boromir totaly up to who you like)
1 minor hero (could also be a banner or captain)
1 core untis (warriors or gondor/rohan)
1 riders of rohan if you choose rohan or rangers if you choose gondor
1 special units (like citadel guards/osgiliath vets/rohan royal guard ect ect)
this structure will give you also a complete small army for your first games