Think this really depends on what you're "looking for" (pun intended).
There are examples where Geordi has the clear advantage (as mentioned by Richard: Generations being one example with the hidden door).
However, it's never really explained how Data sees things (as far as you could consider his perception seeing).
Geordi's vision is clearly augmented and he's unable to see "normally" (at least if you skip the latest movie adaptions, where he's got in-eye implants).
In Data's case I'd assume his vision is artificially limited (unless specifically modified for plot reasons), simply to make him more human.
So if you're looking for things invisible to the human eye, I'd guess Geordi has the advantage.
If you're talking about normal things perceivable by the human eye, Data seems to have the advantage (at least when considering "Visor Geordi").
scifi.stackexchange.com/users/4154/Mario
Geordi's vision is better Per Compro01's comment about "Encounter at Farpoint", Data himself indicates that he considers his own visual abilities to be inferior to that afforded by Geordi's VISOR (which can apparently register electromagnetic signals across the entire EM spectrum between 1 Hz and 100,000 THz)
It would seem that Riker also concurs.
RIKER:
Tasha, you and the Counsellor.
And, Geordi, I want your eyes down there.
(to Data)
You and I will start with topside.
(As the three explore underground) RIKER: Have you noticed anything unusual?
DATA: I can't see as well as Geordi, sir,
but so far the material seems rather very ordinary.
Although Data does appear to have unnaturally good visual acuity (including depth measuring, the ability to "see" people's respiration rates and patterns, etc)
there's no real indication that he can see any better than the average human.
And in the original script for Star Trek : First Contact
we learn that although Data's vision is noticeably better than a normal human's (and that he can also see beyond the ultra-violet and infra-red)
this certainly doesn't compare with Geordi's range.
We follow his hand as it comes up and touches his FACE, which is also FLESH.
The gold color is gone, his hair is tousled and natural-looking.
Even his eyes are real now -- blue.
He touches his face tentatively, his expression confused... but intrigued.
As he talks, we can see that he's becoming seduced by his own newfound senses.
DATA : My visual acuity has been reduced by seventy-eight percent...
and I can no longer perceive light beyond the ultraviolet or the infrared... (beat) But I can see
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To add further evidence to support the contention that Geordi's vision is better than Data's, in the episode Hide and Q , both Geordi and data are looking for Worf and Geordi is describing the scene: RIKER:
Geordi, can you see Worf? LAFORGE: I'd see the freckles on hisnose if he had them, sir.
He's at the third ridge.
DATA:
The third ridge? LAFORGE:
Moving well too.
Oh,
oh.
Good, he sees them.
(Source)
emphasis mine
The fact that Data is asking Geordi about the situation, as emphasised, suggests Geordi's distance vision is also superior to Data's.
scifi.stackexchange.com/users/22917/Often Right
I have some experience working with industrial assembly line cameras; those cameras can make amazing calculations on very little visible data.
Similarly, I think that Data's better-than-human vision does not come from better recording equipment (eyes), but better processing.
The human brain is adept at picking out patterns and differences; when Geordi found the hidden door (as mentioned by Richard), his human brain was able to quickly isolate and process the relevant visual information.
Data, on the other hand, has an advanced information processor; just like industrial cameras, Data may not be great at spotting tiny details on the first pass, but he can add post-processing filters and do side-by-side comparisons that no human could ever handle.
That is how he can accurately measure distances or sizes with only his eyes; he could measure a heartbeat by comparing the difference in pixels between frames in a heavily post-processed video of someone's wrist.
Thus, I believe that while Geordi may have a much wider vision spectrum, Data would easily be the fastest at a "spot the differences" puzzle.
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While it isn't necessarily a canonical source, the ST:TNG video game for the SNES, Genesis, and Game Gear provides an idea of how well Geordi and Data see in the dark.
In the game, Geordi sees better than Data in the dark, and both of them see better than the other crew members - which sounds like it meshes pretty well with what others have mentioned from the series.
scifi.stackexchange.com/users/15980/Matt LaFave
I know that Geordi's blind, but with his VISOR, he has exceptional vision with a range for a wide subspace spectrum.  How does this compare with Data's android vision: Does Data have a comparable vision of the spectrum to Geordi, or is he limited to standard visible light like humans?
Who can see better: Geordi or Data?
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<star-trek><star-trek-tng><star-trek-data>
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scifi.stackexchange.com/users/22917/Often Right
Data's vision may be artificially limited to make him appear more human.  However, he does seem to have better vision than Geordi. However, Geordi sees better than Data in the dark, and both of them see better than the other crew members and there is some suggestion that suggests Geordi's distance vision is also superior to Data's. In terms of seeing better by the human eye, it is clear Data’s vision is artificially limited, which renders him more human. However, Geordi, on the whole, has superior vision to Data. 
In terms of seeing better by the human eye, Data has the advantage. Data’s vision is artificially limited, to render him more human. The fact Data asks Geordi suggests Geordi has superior vision. 