Tax cuts put money into the hands of people who will spend or invest it on things that are economically valuable. The money goes into the market system directly or indirectly.
Spending increases divert money out of the market system and into the sausage factory. In this world, swimming pools and tennis centers are "infrastructure", companies that have been failing for 20+ years are given billions of dollars and a mandate to undertake even less profitable business plans, bridges are built "to nowhere". We're lucky if the "multiplier" on this crap is as big as 1.0.
People, our government produces mass quantities of a particular product: pork. And every time it increases output, the arteries of our economy get a little bit more fatty and clogged.
On average tax cuts free up more money to go toward more highly valued uses (at least if they reduce spending or are given to non-Ricardian agents).
If you are wondering what I am ranting about check out this, this, and this.
I guess I'd rather give my money to people who are going to use it to try to make more money (i.e. save/spend it in the market system) than give it to people who are going to use it to try and get re-elected.
Hat tip to Tyler for getting me wound up on this subject.