I am not quite sure if I should look at 'N' scale - due to limited space - what do you and any other readers advise? HO or N ?
Scale and gauge is a very personal choice, and it's influenced by a lot of factors. Here are a few to consider:
How much space do you have available?
What do you want to model? Mainline, branchline, logging, shortlline? Obviously if you're modeling a small branch it will be easier than if you plan on modeling modern 100 car long intermodal trains.
What do you want your layout to include? Will one or two detailed scenes be enough, or do you dream of a station, and enginehouse, and a yard, and a mountain scene, and a town and a city scene, oh and a steel mill, and coal mines for the mill, and... (How much room do I have again....)
What models do you want to purchase and what scales are they available in? If your favorite line's best known engine is only available in HO, that may well influence your choice.
What features do you want? DCC and sound for example are both easier in HO than in N, and the sound quality is better too.
Do you plan on scratchbuilding or super detailing? If so, and you want to model in N scale, do you have the patience and skills of a watchmaker?
How well do you want the detail to be visible. I don't know about you, but sometimes I have to squint at the really small stuff to tell what kind of steamer that really is.
Personally, I've chosen HO, for a variety of reasons, including an existing collection of rolling stock. I often wish I modeled in N scale when I'm desiging the track and wish I worked in O scale or even G scale when I see the detail you find on the big stuff, so I guess HO is a reasonable compromise for me.