Besides number of slides there is depth, length of slides and so on. Do not forget that these things do require maintenance and repair. I am currently getting my bedroom slide rubber seal tucked back in. The front one required 2,200 in repairs last year (most paid by extended warranty).
I would have to comment that the new full wall slides are very impressive. We just saw Entegra and two American coaches with full wall slides at a show in Tucson. If we were to look at a new motorhome, which we are not, but if we were a full wall slide would be attractive.
Our current motor home only have two slides, but the layout for us is great. Our bedroom is very large with tons of closet space. Our living room is fine for us. It is not as wide as some of our friends coaches. What is really nice about no passenger side slides is that you can get into the basement storage really easy. No overhanging slides in the way. Plus the patio does not have a big slide in it.