Besides the 31 and 100 point levels recommended in the rule book, what different point levels seem to work the best?  Are there any levels that should be avoided because it gives one side an advantage when building forces?

For example, 40 points gives a fully upgraded Wedge; does 40 points on the Imperial side allow for a balanced build that should be equivilant?

40 points is a bad point total for the rebels, at least for Wave 1.  It either means you have to run 1 ship, or you run two Y-Wings without ion cannons (yuck).  

For 40 points on the Imperial side, you could run Dark Curse and two Academy Pilots. In 3 versus 1, I'm guessing the favor would land on the Imperial side.  Wedge wouldn't be able to get a ton of use out of R2-D2, otherwise he would be a sitting duck for the imps.  A lucky proton torpedo shot might throw the round to his favor though.  Give it a try, you never know!

i like 55 points. 50 and 60 points favours the imps too much, and other random numbers like 57 etc seems a bit weird. 65 to 70 favours rebels a little too much

So 31, 55, and 100 are recommended balanced point levels.  What would you consider balanced closest to 75?

I've heard of some people generating a random point total by rolling a D10, and either adding or subtracting the roll from 100. You could even buy a fudge dice with + and - symbols to help with this. :)