From your perspective, you just want more money. So you can ask for more money: either in terms of base, benefits, or signing bonus. But uou need to look at this from the employer's perspective. Do they have a general 'salary band' for people at your level. If they do, and if you're asking for a base above this band, then a signing bonus is a way they can give you more without breaking their band. Also, for the employer to hire you at a high base entails a risk: if you don't perform then they're stuck with paying you a high salary. But if they just give you a signing bonus and you don't perform, they just need to pay you your lower base next year. Same applies to annual bonus: if this is calculated as a % of your base, then giving you a lower base is better for them. And consider next year's pay-rise: if this is also a % of your base, employer would prefer you to be starting on a lower base. So its always better to get a higher base than a joining bonus, but if they won't budge on base then there's no harm in asking for a signinf bonus to 'bridge the gap' between what you want and what they want.
