If you want to show-off then definitely go with the Mazda RX. Far more flashy than any Civic, riced or not. Although its rotary engine is a total pain in the bottom to maintain. It also eats a lot of petrol and burns oil like crazy!
Whereas if you want practicality then go with the Civic. More seats and MUCH more reliable engine.
Both cars are over a decade old at this point so it's best to go with a used WagonR, assuming your budget is 1 million+. Sure, it won't have the 'cool' factor of a Mazda RX, but it'll be FAR more practical and fuel efficient.
Alternatively, you can easily find a 600-750cc 4-Cyl crotch rocket for around 400-600k such as the Suzuki Katana 600, 750 or Yamaha YZF600R Thundercat etc. The 1998 Katana 750, for instance, does 0-60 in 3.5 seconds, 0.4 seconds quicker than the Dodge Challenger SRT Hellcat and 0.2 seconds quicker than the freaking Lexus LFA, and it's not even a sports bike! More like a sports tourer.
Go the Gixxer, ZXR, CBR or YZF-R way and you're looking at <3.0s 0-60s with razor sharp handling.
There's a reason I love motorcycles...