these are my current ones

these are the smaller 16 inch ROH ones i'm thinking of swapping to

 

You should also account for old and new wheel offset. Both for looks but also to make sure they’ll even fit.

 

I don't like the wheels you have now, so in my opinion yes they will look better.
Also in my opinion, the stock S5 TII wheels look better than either of those two options

 

IMO the problem isn't that your wheels are too big, it's that your tires are too small.

 

just in general the proportion between the car and wheel makes a big difference. the small wheels emphasize the car, and tend to make it look longer and maybe lower. big wheels make the car look shorter and taller (and sometimes cartoony)

 

I think the rims you're considering switching to look better than the ones you have now, but that the new ones still aren't quite right. Just my opinion.

I was also looking into 16" rims and found that the tire availability wasn't great, so that's something to consider. IMO 17" looks good on FCs and has a wide selection of tires.

I have tried 18" rims, you can pull it off but it starts to look like a covered wagon after that unless you have very large brakes to justify it (again, IMO). I'm sure someone out there has pulled off larger rims than that but I've never been a fan of oversized rims with skinny tires myself.

 

i tried to find some pics, and these kind of work. i was looking for something more extreme. both cars look good btw

 

Depends on what you want to do with the car. In my personal opinion, I think both sets look.... meh. But, that is just my opinion. You do have a plethora of wheel choice options with 5x114.3. If you want some inspiration, there is an entire thread dedicated to FC wheel fitment/pictures @

RX7Club.com - Mazda RX7 Forum>Tech and Performance>Suspension/Wheels/Tires/Brakes
>The Official FC Wheel Fitment Thread