Slides do not necessarily leak.
We have 3, 5th wheel is 11 yrs old and NONE have leaked ---ever.
Properly adjusted and seals maintained---no leaks
Maintain seals? I dust mine using an old sock filled with talcum powder.
Roof leaks.....
One can be proactive and maintain caulking at seams and/or clean/cover with
EternaBond Tape ----goes a long way in preventing issues with leaks
So decide on the floorplan, size, weight and then be 'proactive'
ALL RVs require maintenance and upkeep.
More proactive owner is the better the RV