There's quite a few differences between the waddlers and the space so its hard to just say one is better than the other. You'll have to compare their features and decide which is the better value for what you want I guess.
Waddlers are thinner and stiffer when dry. Although they fit "a little boxy" at first, they seem to quickly adjust their shape and are very comfortable. The ability to move the tapes many times isn't that big of a deal, it's not like you need to move them every 10 minutes. If I'm wearing for a long time I will need to make one or two adjustments before it's time to change. The adhesives on the space don't seem to have a problem with a few moves. So I don't consider the "refastenability" to be that big of a deal with the waddlers. at least when compared to space. Some other diapers aren't as good with moving tapes - bambino for example aren't nearly as reliable after moving a tape, and waddler tapes definitely have the advantage there. The tapes are also wider, and I've never seen a tape fail on a waddler for any reason.
But that comes at a price, the entire "tape panel" area on a waddler is a bit rough. Space tape panels are harder, waddler are rougher. Decide what you do and do not like there.
Waddlers size a little smaller, and are closer to my ideal size than space. It's not a big difference, but that, combined with slightly more flexible and stretchy shell, the waddlers seem to fit a little more comfortably for me.
Wadders are a little more discrete when dry. Also because of their looser fit you will probably need to adjust the tapes to prevent sag and slip after it gets very wet. Space can usually stay up without an adjustment for longer.
They seem to have a similar capacity overall, but space wick better and feel slightly wetter, waddlers don't wick as well, swell more, and feel a little dryer.
In the end, for me anyway, for several reasons the space work better for overnight and waddlers work better for daytime. I find the space are a bit too thick for me to wear comfortably under pants, and the waddlers are rougher on the wrists and slightly more prone to leaking overnight.
A few bucks more a bag doesn't seem like too big of a price difference to me though. They're both good diapers. So I'd say get what works better for you.