One of my best friends had a 2018 WRX, and now a 2019 WRX STi. I have ridden in and driven them both.
My impressions: 2018
The interior is "meh" at best. Not anywhere in the class of rivals at this price point.
Handling is excellent
Transmission/clutch are quite good
Power stock is pretty "okay", and totally blah for the money spent, considering rivals at this price point. It's basically the same as a CX5 Signature/GTR. It isn't as laggy as the STi, but there is still some nasty lag that a good tune will do well at hiding. MPG is pretty decent, in the mid 20's for daily use.
In short, it's a fun AWD vehicle, but it's interior is very "meh", and the power would have been pretty solid back in 1995. I personally am not a fan, overall.
2019 STi:
-Interior is MUCH better, more in-line with contemporaries.
-Handling is EXCELLENT. Very fun car. Controllable and willing!
-Power is VERY laggy. If you're in the wrong gear or get caught after the clutch is fully engaged in 1st at a low speed, you're just a dead duck. Absolutely gutless below 3000rpm. After 3000rpm, it's quite good. I would say that over-all, the car is on-par for 2008 or so's standards. Sadly, the mpg is absolutely HORRIBLE, my friend averages around 17mpg daily driving, and when asked what the BEST he could ever conceive it getting if he refused to have fun in it, he hesitantly replied "around 20mpg".
-Mechanics, the transmission is quite good, as is the suspension. Whoever said these are "too stiff" can get bent. They aren't. They are about perfect. The clutch, on the other hand, is a raging pain to operate smoothly and well. If you test drive one, you'll "get it". 90% of the engagement happens in the last 10% of travel at the top. Horrible.
-Road noise and exhaust drone are...palpable. I would not want to road trip this car.
Overall, the 2019 STi is a car worth owning, although its time came and went in its current configuration, about a decade ago. The base WRX is a boring sad sack and I'd much rather have a CX5 GT-R/Signature 95% of the time, that other 5% of the time being in the corners.
2018 WRX, per Motortrend:
-60 MPH 6.2 sec
QUARTER MILE 14.5 sec @ 94.2 mph
BRAKING, 60-0 MPH 113 ft
LATERAL ACCELERATION 0.93 g (avg)
MT FIGURE EIGHT 25.2 sec @ 0.72 g (avg)
EPA CITY/HWY/COMB FUEL ECON 21/27/23 mpg
WRX Sti, 2018, per Motor Trend
0-60 MPH 5.7 sec
QUARTER MILE 14.1 sec @ 98.5 mph
BRAKING, 60-0 MPH 109 ft
LATERAL ACCELERATION 0.93 g (avg)
MT FIGURE EIGHT 25.1 sec @ 0.75 g (avg)
EPA CITY/HWY/COMB FUEL ECON 17/23/19 mpg
Keep in mind that the STi takes a 2nd shift to hit 60mph, and that the 2019 models received some suspension refinements and engine refinements (resulting in 5bhp more, allegedly)
CX5 turbo, per Motor Trend:
0-60 MPH 6.4 sec*
QUARTER MILE 14.9 sec @ 93.6 mph*
BRAKING, 60-0 MPH 125 ft
LATERAL ACCELERATION 0.79 g (avg)
MT FIGURE EIGHT 27.7 sec @ 0.62 g (avg)
REAL MPG, CITY/HWY/COMB 23.3/32.2/26.6 mpg
EPA CITY/HWY/COMB FUEL ECON 22/27/24 mpg
My opinion? Get the STi, but NOT for a daily. Otherwise, hold out for the redesign (this would ultimately be my move, regardless, as the STI just has so many rough edges and all it gives in exchange is a competent AWD system. Literally everything else can be found in more abundance, for cheaper, in other cars). Also, this is a car for someone who can drive. If you can't, then don't waste your time. Its bad traits far out number its good traits for you. It's definitely an enthusiasts car, and not a car for someone who wants a decent daily "that is also fun". For that person, the Charger would make a lot more sense, or a Mustang GT, or a Camaro, or any number of other vehicles with a bit less "personality".
THAT SAID...
I am pretty much "JDM or I won't touch it" at this point, and the only other alternatives are the Supra or 370Z. The 370Z has also had its day, and I owned one, and I'll never own another, or another Nissan for that matter. They are the Chrysler of Japan. If someone held a gun to my head and demanded I get a JDM sports car, it would be the Sti.
Also, don't bother with anything but the highest level of trim, otherwise it's terrible inside with no tech.
This video PERFECTLY demonstrates the dead-duck low rpm performance of the STi:
Now compare this with my personal 5-60 in my CX5:
The CX5 has wonderfully low (no?) levels of lag.