Two of the longest romantic comedies from Jump... which to read? A comparison is unavoidable.
If you look at my comment on the Ichigo 100% page, you will see my thoughts on it being the genre defining masterpiece. Let's look at Nisekoi: it's longer, it's more modern, it doesn't sound as lame... looks good.
The premise of Nisekoi is captivating and I can tell you right away the ending is great. Regardless of who you ship, the ending was well written, and in addition it brings a progressive message on romance (not that I fully buy it, but I'm no love expert). The art is polished and suits the genre.
However, Nisekoi falls short. It is soon apparent that the characters and the plot developments are unrealistic and forced. Let me explain why.
Every single character is a genuinely, deep-down-to-the-earth good person, in an idealistic sense: "anything must go through great lengths to be patched up because we must get along as best friends 100% of the time *smiles". And so the manga is filled with a ton of cheesy lines and fluffy resolutions.
Being a rom-com, the author implements comedic tropes and scenarios quite often, even in major plot developments. The result is that the story is often episodic and the predictable developments feel forced and spontaneous. It is hard to take even some of the crucial parts of the manga seriously.
Of course, if you have no problem with both cringe character lines and story lines and aren't looking for an immersive experience, then go for it. It's mostly all comedic fluff and positive feelings between the characters rather than drama. Do bear in mind I can only really say that the beginning, the first 20 chapters or so and the ending, the last 10 chapters, are of good quality. That puts around 200 chapters up in the air so it does drag on.
I have reread Ichigo 100% many times. Just reading Nisekoi once was a chore.
With all its cheesy and unnatural aspects, Nisekoi really is a fake love story.