Here is my two cents, even though I've only owned a pop up, then a 5th and soon a second fifth. This is how we decided on our campers which may help you think through yours.
If you are asking the question, my guess is that you are thinking about the room and you'll find the smaller one cramped. Slides make a world of difference!! How old are your kids? If they are young now, the camper will only get smaller as they grow up.
Some people are minimalists and not having the slide doesn't matter. What type of person are you?
We got a 33' fiver as our first camper after the old pop up. Ordered it new when my son wasn't even walking yet. It was an entry level bunkhouse fifth wheel. DD who was 3 going on 4 was really excited to sleep on the top bunk. The couch and dinette where on one big slide and really opened up the main area. Never had one problem with the slide over 9 years and 45,000 miles. This was the biggest trailer by far that I have towed. It towed nice and ended up getting very comfortable with it in no time flat. It served us well for those 9 years, but it was falling apart and wasn't fully working for us anymore. The bunks were narrow and the kids (12 year old daughter is 5'-11" and son is going to follow suit) took to sleeping elsewhere, leaving a huge waste of space. In the end, I expected to get next to nothing on trade given the issues on it. I ended up getting just under half of a camper we paid $21k out the door on.
A camper is going to depreciate. The more you trade, the more you loose. The longer you keep it the less it is worth. You have to think about it as a vehicle. We tend to keep vehicles until they hit that point where they are no longer reliable (nearing 200k miles), aren't worth much and then buy a new one. I got a lot more enjoyment and memories out of the camper then I did any vehicle that I have ever owned.
That is when we started looking. The 29.5BHDS is what we feel will serve our needs. Gives the kids full size bunks (750 lb capacity) that will support them until they are done camping with us. Gives them their own storage for their clothes. Keeps them from sleeping in the living area. Gives DW an outside kitchen. This will hold us over until the kids are gone and then we'll probably trade for something without bunks. A lot of things change in campers over the course of several years.
Some people will trade every couple years looking for what is right. We didn't want to do that and are pretty comfortable that we got our money worth out of the first one and enjoyment as well. We feel pretty certain that this will be the case with the next one.
If you are in it for the long run, I'd think about one with a dinette/sofa slide. Hope the ramblings of our decisions can be of help to you!!
2016 Jayco Eagle HT 29.5BHDS (ordered 12/30/15, delivered 3/8/16)
2015 F-350 crew cab, short bed, 6.7L PSD, Pullrite Superglide 3300 hitch