For his first RV, my brother bought a Class C without a slide. After using it on several trips, he traded it for a slightly longer C WITH a slide. Although it is technically not that many square feet added, for me it is a "psychological" feeling of much more space added when a slide is included.
As others have stated, you will probably sacrifice some storage as far as weight is concerned. However, that may actually be a good thing. It is very easy to cram most everything you think you MIGHT need into any kind of RV. After several years of short term RVing, my wife and I found out that we carried way too much "stuff" in the RV. Once you put it in there, you are basically just hauling it around and probably don't even remember it is in there.
Regardless of what you choose, travel as light as possible.
One other possibility is to rent an RV without a slide for a few days and see how it feels. The only one who can make the choice is you and what suits your needs. Good luck with your search.