Which job to choose?

I wouldn't especially recommend either. I've also interviewed with both, but didn't take either. Both Statestreet and IFS have been implementing a policy of acquiring other smaller fund companies. Invariably, people who have worked in the smaller fund companies say that although they're usually paid better after the takeovers, working conditions tend to take a nosedive - very long hours etc. In IFS, they offer free lunches, but this is only to encourage you to eat at your desk and skip your hour's lunch. My impression of Statestreet is something similar, although, I don't know anyone who works there at the moment, so someone else might be able to tell you more.
You'll need to find out exactly what you're doing in both. IFS split their tasks, so that instead of valuing an entire fund, you work on one small part (for example you might spend all day, every day, working out the margins on futures). Not only is this soul-destroying, it won't be as good on your CV when you're looking elsewhere, as being able to show you have a grasp of all aspects of funds (as is the case with most companies). Finally, you should find out what system each company uses. I seem to remember that IFS use an in-house system, which isn't used by any of the other companies in Dublin. Again, for your first job, I'd probably avoid this situation, as the skills you learn on that system won't be immediately transferrable. Probably one third to a half of all fund companies use Sungard (also called Wins / InvestOne), so if you have a grounding in this you'll be in a better position when looking for your next job.
On the upside you can move up in both companies quite quickly and earn quite a lot relatively quickly. Overall though, if you've interviewed for other companies that offered slightly less in terms of starting salary, you shouldn't rule them out entirely if you got a good feel for the place. The extra 20 quid a week isn't going to make a huge difference, but the working conditions might.

Not sure what starting salaries are now. I'd reckon 23-27 grand depending on the place.
Starting off, in funds you'll definitely be earning quite a bit more than training with an accountancy firm. After qualification as an accountant, you might still find yourself lagging behind in terms of wages, as with 3 or 4 years experience in funds you can expect to earn 38-45k.
The downside is that despite the tax advantages to fund companies of locating here, Ireland is getting to be an expensive place to do business. Already a couple of companies have set up in Poland and long-term, the prospects mightn't be great in funds. However, the companies that are here are well entrenched and in general expanding their businesses, so it's very unlikely there'll be any mass exodus in the next 5 years at least.
On balance, having worked briefly in accounting, I'd recommend funds, as the stereotypes definitely hold some water. I wouldn't let the wages sway you too much though - if you reckon you'd enjoy accountancy, it's a safer bet and will likely open more doors in the long run. If you don't think you'll stay in accountancy, I'd say you're better off avoiding it - it's a lot of work and hassle to go through just to jack it in at the end.
As regards jobs in a bank- this can mean absolutely anything. The big Irish banks pay fairly bad starting salaries though

They're known to be kinda boring. There's lots that aren't, but get a couple of hundred of them together in a building and you wouldn't believe the crap they'll laugh at