you need to decide what type of road bike
ROAD RACER - steeper frame angles, higher gears, no room for mudguards. Generally light, fast and built for performance
TOURER - slacker angles, clearance for wider tyres and mudguards, fittings for racks etc., low gears for hauling loads. Generally fairly light weight, but built for comfort, durability and load carrying. Will feel slower than an out-and-out racer, but faster than an MTB
COMMUTER - depends on the terrain and weather you travel in. Might need low gears if its a hilly ride, might want mudguards if your travelling all year, poss fittings for rack and lights. Or you might want a fast-blast to work on sunny days. Might only want single speed. No such thing as one-size-fits-all here.
Then consider frame material
STEEL - durable, can be repaired or repainted, can have rack braze ons added. Heavier than other materials, but comfortable and will have long life.
ALUM - good alloy is light, some cheap alloy import frames arent much lighter than good steel. Not renowned for comfort, but stiff and efficient at transmitting effort. Can be repaired.
CARBON - tends to be performance oriented and expensive and durability is questionable. Very comfortable. No warning of impending breakage.
the choice of todays racers.
TITANIUM - expensive, but supposedly lasts for life with no fatigue. Used by both racers and tourists at top levels. Extremely comfortable. Can be repaired.
Once youve decided the above, based on intended use and budget, then can you make a reasoned choice of complete bike.
You always get more value for money with a well-cared, used bike than buying new.
A bicycle can't stand up on its own as it's two tyred