How're you making your project decision?

There are several reasons and conditions that could surround the appraisal of projects. It could be the case that an investor is faced with multiple projects to choose from OR decision makers faced with one project to either accept or not, OR it could even be the case of a project already underway that needs to change hands and the new investors want to assess the project's performance.
Asides from non-discounted measures like the payback period and the accounting rate of return which are relatively easy to measure, do not factor the effects of time value of money-per the effects of inflation, there is also the importance of analysing project/investment decisions that do require more importantly the knowledge of how valuable/costly net cash flow would be over the life of the project.
In real life, people investing in huge and capital intensive projects require specifics on parameters like what is the risk free rate of interest now versus what's the cost of the capital invested or to be invested in this project? Is there a premium on the cost of capital? Or is the project even going break even at any point in the short to medium term? And at what rate ? This is what techniques like the Cost-benefit Ratio, the Internal Rate of Return (IRR) and the Net Present Value (NPV) can help to answer.
The NPV can give the best picture if the discount rates are as close to accurate during the tenure of the project because it discounts the cash flows over the project life using a specific cost of capital. The downside to this method is the difficulty in being accurate with discount rates and the specific timing of these capital expenditures. So to combat this, the analyst can try to estimate the IRR, in order to give the investor a fair idea of the interest rate at which the project yields on. This ultimately gives the investor the chance to compare alternative investments based on their yields.