What is good online chess or Fritz?

I will go for Fritz because you learn very fast with it and you can enjoy every level of chess .Even it gives you titles like IM and GM or Super GM

I am not in favour of online chess because it tends to hypnotize you.

It is my experiments with truths.

I will strongly recommend youths to abstain from these sites.

They design web sites for retired personnels. The Old guys .

Who just want to get their time passed

I am fundamentally opposed to creating false choices between two things that are not mutually exclusive.

Playing online with real people in better training for OTB than playing against an engine, but the engine is useful for assistance with postgame evaluation. The Fritz interface also helps with database management.

I also find a lot of benefit playing set positions against the engine. See http://chessskill.blogspot.com/2008/11/where-rubber-meets-road.html.

Change your title to: What is good? Online chess and Fritz! 

I think both are good.

Theoretically, I'm sure I would improve faster if I consistently played mainly Fritz (or STockfish) set to +100 my actual rating ability, but in reality, it's nowhere near as fun or as motivating to play humans, so I make that sacrifice.

I will add that I have spent some time playing Fritz set at various rating abilities, and I definitely think you can learn a lot from playing the engines set near/stronger your rating. The Stockfish engine I play also seems to mix up the openings and strategies a lot so the games are surprisingly interesting, not what 'boring CPUs' used to do back in the day.

Never used or seen an engine so I will have to say online chess is more useful. 

There's an option to set a slider in there somewhere.