I'm going with H&R Block's Tax Cut Software...
Just picked up a copy today...
I've always done my taxes the old fashioned way (with 10-key, spreadsheets, confusion, etc...)
Then last year after I had completed my taxes manually, I borrowed a buddy's copy of Tax Cut... It did in 1 hour what I did in 4. I think the total tax due was different by 1 or 2 dollars...
Needless to say, I'm going computerized this year.
