SmithJ;
Are you referring to a one time signing bonus or are you evaluating a company that provides a yearly incentive payout (aka bonus) based on company and individual performance. These are totally different comparisons.
Regarding a signing bonus - this is a one time kicker and to me is of minimal weighting for a job consideration. You get it one time and spend it. One time thrill.
On the other hand, if a company provides a yearly incentive payout that is dependent on company and individual performance, this is something to give much higher weighting. Most companies want to hold the line on O&M costs, so they can do this by controlling fixed costs like salaries. The company may offer you annual cost of living raises with some additional amount for individual merit, potential for job promotions and, if possible, provides a yearly incentive payout.
For example, I worked for an electric utility for about 18 years and they rewarded employees with decent raises, promotions based on a scheduled progression and very small yearly bonuses (most of the time no bonuses because they had to justify expense and capital dollar spending). The value in this system is that I had a defined benefit pension plan, which is based on the last five years of your salary (nothing to do with bonuses, so the higher the salary the greater the pension benefit).
Well, the utility sold there generation some time ago and I decided to go with the new owner that offered annual performance raises (cost of living + some level of merit increase) + an annual incentive payout. Over the last 6 years that I have been with the company, the incentive payout averaged 17% of your base salary. So, one needs to consider options very carefully.
PS; I happened to be in the right place during the divestiture because just as my former company sold their generation, I had qualified for an early retirement package (when I reach age 50, I can collect my defined benefit pension).