LeBlanc is the number one solo target nuker.
Annie and Brand are the strongest team nukers.

best nuker definitly is veigar . followed by lb and akali with double stack build. than annie gp etc...

Veigar the biggest nuke, annie the best nuke.

Galio, his ult is a massive nuke that can hit the whole enemy team (+taunt) + his skills have high ap ratios and good range.

edit: oops did I think outside the box too hard?

1. Veigar
2. LeBlanc
3. Anivia

The USA.

veigar-leblanc as singe target nukers
best nuker ever is a good played fiddle,his damage over time gives him low burst damage but immense ammounts in due time,making team battles so much fun combined with all that cc

i will agree with veigar and leBlanc .. And i would and karthus to those .

Early game, Brand.