I ate recently in Greenes on MacCurtain St. and got a lovely meal. I've never been to Jacobs or Ivory Tower (at least not yet) but both always get very good reviews.
It depends your taste obviously but le gourmondais on cook street is absaloutly fantastic. As is the restaurant on bridge street whos name escapes me.... market lane on Oliver plunket street is lovely too!
Les Gourmandise is very nice but also very pricey, last time I was there the bill was over 450 and did not do anything insane, ie 3 courses & probably 3 bottles of wine.
Star Anise is the restaurant on Bridge St and the food is very nice on the few occasions I have been there.
Best of the lot for food in my experience is Ivory Tower but it is expensive.
Eco's in Douglas, fantastic menu, wonderful romantic setting, brilliant service, amazing quality, and cheap as chips. Honestly, you should try it yourself
Definitely Cafe Paradiso. The food is out of this world and I have often given gift vouchers as gifts as its a place people might be fearful of due to the absence of meat on the menu and not 'chance' it on a night out. However if someone's bought a voucher for you, you've nothing to lose.
Every time I've been thanked most sincerely.