If you go 15inch rims, my picks

All rounder: PS3

Super excitement: Advan Neova AD08r  (supergrip, but FC gonna suffer a bit, rain becareful)

Sexy looks: Yoko S Drives...hard to beat this classic..pictures dun do justice...see it real life

Budget all rounder: Hankook V12 (when new its as good as PS3, but performance goes down fast after half life)
I've used Hankook EVO S1 tires and like them. Now got S2 EVO.
Hankook tires does the job well, but without the finess of more Premium tires.

Daily drive: XM2, Cdrive 2.

I prefer using 195/55/15 instead of 195/50/15 cos of roads too many potholes.

If you insist on FC and some good grip: 185/55/15....good news is PS3 also have those sizes

If you go 17inch then got more exciting tires for you...that where the fun starts..but need to change your car first.

1. Is your car still under warranty? If yes than you will void the suspension warranty if you change to other rims.
2. Normally ppl change the rims for a number of reasons, mostly for looks and performance. By going 16, you will sacrifice the comfort. And the rims will be heavier unless you buy those light weight rims.

Just stick to what you have, XM2 are fine tires for family category.

But if you are thinking of performance, than ok to go for 16inch and fit em PS3 or PS4 if its available.

P3ST is also available, but the sidewalls is a bit soft even though it grips better than XM2.