I think they've all put out some really top quality titles. But my favourite right now would be ngmoco - I find what they're doing the most interesting.
Had to vote for Chillingo. I looked through all the games that I own and they publish the majority of them.
Technically, EA and Gameloft are the only "big" developer/publishers on that list. ngmoco, despite being iFund funded, are not anywhere near as flush with cash to burn as EA and Gameloft. And Chillingo is smaller still, and barely even develops any of the games they've published (if they developed any at all, which I can't recall). But I guess you meant "big" in terms of overall "production" (apps for sale). If that's the case, honestly...Digital Chocolate needs to be on the list too, regardless of what one may think of their games. They have as much product out there as those listed, and are consistent sellers. Regardless, I'd go ngmoco. Good games so far, and they at least try to take advantage of the unique properties of the platform and build games around it rather than shoehorn games that work on other platforms onto this one with mixed results. BTW, if Sega had their friggin' act together and realized that they are, y'know...SEGA...this wouldn't even be up for debate. They've got the brand recognition, the IP catalog, and a gameplay design philosophy that the others wouldn't compete with. Sega is, after all, a company built on arcade reflex gaming that works so well for mobile gaming, and one that was at one time at the forefront of spreading "social gaming" and game downloads and DLC to boot. But Sega...Sega doesn't "get it". They just don't get that they're, y'know...SEGA!
Yeah I want them to bring Prince of Persia Classic tot eh Iphone. Chillingo's definitely giving them a run for their money though.
Chillingo and Ngmoco. Gameloft and EA seem to specialize in trying to force big franchises from other platforms into working on the iphone, whether or not the controls or gameplay make sense for the format. I think that's annoying. Oh look it's prince of persia or halo or whatever for the iphone! whoopee! Chillingo and Ngmoco seem to have produced or supported more games that actually make good, creative, innovative use of the iphone/pod devices' strengths. Between the two of them, I don't really have an opinion. I guess I'd choose Chillingo if I had to, because they've been involved with more of the games I own right now.
Between EA and Gameloft Both EA and Gameloft make really good quality games such as Need for speed and Assassin's Creed, but I think EA take it out only just, because of the level of polish and depth in their titles. They don't really compromise for the iPhone. And Tiger Woods and NFS are my two favourite games right now. The sims 3 looks incredible too. Ngmoco only have Rolando, but TouchPets and LiveFire both look really good. It seems to me that Chillingo basically just make knock offs of other games (like Mysterious Island), but the graphics they have it their games are really good.
Poll is looking pretty good. Nice to know that the community is divided amongst the developers (as far as picking a current best). Makes for healthy competition.
In order: 1. Ngmoco consistently make above average games that have been designed specificly for iPhone and iPod Touch - no ports here! They tend to be priced according to their true value; not just what they can get away with like EA and Gameloft. Also, they update their titles reasonably often and their future lineup looks awesome (Star defense + rolando 2). 2. Gameloft make some awesome games (Hero of Sparta, Terminater + Guitar Rock Tour), but also some pretty bad (Asphalt 4) or lazy ports (Wild West Guns). They often start off overpriced (especially terminater) and they rarely update either. 3. Chillingo have a wide variety of titles, but are very hit or miss (i.e. Zen Bound vs io). They need to have more quality control measures in place - I mean who the f**k let io slip through? Also their website completely sucks donkey balls. 4. EA, I'm undecided about. Most of their games i've either not tried, don't want to or didn't particularly enjoy (Spore, NFS). Also they seem to release some games only in particular areas (i.e. Pandemonium). Maybe when the EA sports titles like fifa and SSX come out they go up in rankings?
Chillingo. Nothing else even comes close. They have the best (and cheaper) games. Why: EA - Not as bad as Gameloft glitches-wise. There games are slightly better. Not the worst publisher Gameloft - Really bad glitches that make the game unplayable (or nearly) and take like 3 months to fix. And only a few great games imo. Ngmoco - Well I suppose they aren't really glitchy. But having ONLY freemium games, and cancelling Rolando 3. That just makes me f***ing mad!