Best cities to live in Reunion Island

It really depends where you have to work.

If your job is in St Denis (North)
The east part of the Island is actually quite nice an affordable to live in. I don't recommend the western part of the Island (ex St Paul) if you have to work everyday in St Denis, because the traffic jam can really be a nightmare and exhausting on a daily basis

if your job is in St Gilles (West)
There are many nice cities (La Saline, Hermitage) close by and less expensive than St Gilles (per m2), St Leu can also be an alternative, takes about 25min to drive and no need to take the highway.

If your job is in St Pierre (South)
There are also many nice cities, if you don't mind driving a bit, l'Etang Salé (between St Pierre and St Leu) is a gorgeous little town, L'Entre Deux is also absolutely stunning.
If you want to get away from the heat, La Ravine Des Cabris, and La Ligne des Bambous are nice only if you are in a cool neighborhood, houses are really close to each other.
Trois Mares is the best to me, as it's not too high and still hot enough.
You'll also find Grand Anse, and Petite île south of St Pierre, gorgous places to be surounded by nature.

If Your job is in Le Tampon.
The cities mentioned before for St Pierre could work.
I recommend because it's closer L'Entre Deux, La Ligne des 600, Trois Mares, Tampon Center Town, 12 and 14 km.
If you like montain views, cows, horses and having a fire place warming you up on a tropical island, than La Plaine des Cafres could work for you, the weather can be tricky though.

Hope this comment has been helpful

James