The little 13/15" deltas (actually made by invicta) are a nice upgrade from the lunchbox planers. Heavy enough to do a bit of work but light enough to move around on casters. They are the origin of all the 15/20" import 4 post planers that proliferate the market. They certainly have their share of shortcomings but for the price are good machines.
Lots of options on the used market depending on space availability and needs.
Edit to add, bigger is usually (or can be) cheaper. Lots of industrial 24" machines for less than the price of a new 15" 4 post.
This was 1/2 the price of a new 735.