As already been said it depends on your needs...
If you want a TV for mostly daytime viewing or you are going to watch it from different parts of a room than IPS is probably better for you.
If your TV viewing mostly at night and your sitting position is in front of the TV you probably would be better with S-PVA.
S-PVA definitely better in this regard.
2. Color accuracy
Both technologies are very good and comparable.
Personally I think latest IPS panels from LG and especially Alpha have a slight edge over S-PVAs (in a comparable price category).
3. Resistance to color shift when viewed at different angles
IPS panels are better in color shift tests. Go to any Samsung or Sony LCD forum and you'll see complains how bad viewing angles are.
However, IPS panels suffer from some light bleeding when viewing at angles. That's the drawback of IPS.
4. Resistance to motion blur
IPS is slightly better, but latest S-PVAs almost comparable to IPS in this regard.
One other note.
S-PVA technology prone to dreadful flashlighting and clouding effects.
About half of S-PVA based TVs suffer from this (at least according to polls here on forums). It is a inheritable illness of this tech.
And as I noted above IPS panels have viewing angles light bleeding .
Nothing perfect in this world. You chose the imperfection.