Ive owned at various points the acer aspire one, samsung n10 and eeepc 901.
Apart from the odd diffrence like wether they are fitted with bluetooth or 3G their all pretty similar except batter life and keyboard.
The battery life is surperb on the n10, lasting 4 to 5 hours, the keyboards pretty decent too.
The aspire one has a fantastic keyboard which i was just as happy using as a full size one, unfortuantly the battery only lasts around 90 minutes.
The eeepc has got quite a cramped keyboard and not something you`d want to use for lots of typing, the battery life is pretty good though with it usually lasting around 3 hours. This is the one that i currently use purely because it has internal 3G and does seem a little more rugged than the other two.
Theirs quite a few more these days but if battery life is your main concern i cant see many beating the nc10.