You have experience with bicycles, not a noob; therefore, dabble in the used bike market. Best deals for someone who knows what they want & best fit.
Agree with steel frame, especially if used and one with clearance for the tires you want to run. Wheels and tires should be appropriate for your size. 28mm minimum or 32mm tires on sturdy rims with 32 spokes. Good wheels can be maintenance free for years for most riders - except for high mileage or bad roads conditions.
I would also agree about not getting caught up in petty discussion about: 105 vs Tiagra, or how many gears it has. Just get one with the gears to get you up the hills/mountains you will ride. Triple chainrings or a wide range cassette on a compact double will likely yield similar results.
Also recommended if possible. Try riding a road bike (from a friend, club member, or a one day rental) so you can feel the new position and how it affects your body. Then you will be better able to address issues before coming to the 'Buying Moment'. How tall a stem? Narrow or wide bars?
If you really begin to get into road cycling, the 1st roadie is never the last roadie. It's a progression for everyone. ATMO
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Vintage, modern, e-road. It is a big cycling universe.