You can install either Suburban or Atwood.
It's just easier to stay with same brand/same size as the framed opening sizes are different.
Both have their good and bad.
Suburban....glass lined/steel tank...need anode rod
Atwood....aluminum alloy tank...no anode rod
Suburban.....separate set of t-stats for electric and propane
Atwood...only one set of t-stats for both electric and propane
Lower preset t-stat on Suburban vs Atwood....other preset temps available and Atwood has an adjustable t-stat replacement.
Suburban.....3/4" drain hole (because of anode rod)
Atwood......only 1/2" drain hole
Other than that not much difference between the two.