You have to write down what you want from a car and then start eliminating from the list
RWD? Civic or Mazda3 is out for example
Turbo or N/A?
Practicality & comfort important ?
How important is handling or good car behavior ?
Budget?
Service costs/fuel consumption/taxes etc. ?
Compare to what you already drive
etc.
For example in my case:
I want an excellent handling car (RWD for sure) with creature comforts (A/C is a must here due to climate) and safety equipment (ABS/airbags/Traction control).
I also need 4 usable seats.
So after research I excluded the Lotus Elise, the Miata, the Mazdaspeed3, any Honda etc. etc.
The only car that also has all this is the FR-S.
But I already own an RX8 which satisfies all my requirements except fuel consumption...
An FR-S would be a sidegrade (or possibly a slight downgrade on performance, real life tests will show) and financially it doesn't make sense as a trade-in...
Since I can't improve my RX8's MPG, I found that going turbo on it will give me approximately the same MPG as now (driven in the same way) due to the way a wankel motor works...
I can afford the gas, I do 500 miles a month but I want MORE out of my cash spent...
So in my mind ?
My 18-20mpg for stock 247hp (210 at the wheels, dynoed) - not very good, some may even say unacceptable so I was looking for alternate options...
But if you think about it 18-20mpg for a turboed RX8 with 350-400 (AT THE WHEELS!) + 4 seats + boot ? = sign me up ! I'd even tolerate 16mpg for it
So I'm going this route instead of the FR-S and it will cost me much much less...
You have to be open minded and see all your options
Work with what you want, what you already have, what you need and what you can afford...
Once you strike a balance with these, the choice will be obvious for you...!
I know deciding for a new car is frustrating, time and mood consuming so maybe my way of approach helps you
Good luck!