you mentioned you would like something better w/o spending a lot of money. it also sounds like you want it for pretty basic riding. the lx would be an awesome choice for what you are doing. the nimbus is stronger, and in my opinion is a much better looking cycle too! it may be overkill for what you are doing, but it is an exellent choice, and the cost is easily justifiable by the components.
the models i would consider:
torker lx:
overall very good build, could last quite long under casual use.
-has a suzue square taper hub, not as durable as an isis hub, but has a good track record, and there are many crank arm choices available to fit it. (you probably never need a stronger hub for the riding you described)
-you’ll probably want to replace the seat, it’s shaped fairly well, but it’s hard as a rock.
-rim is pretty strong for a single wall rim
-plastic pedals become slippery when wet, you may want to change them too.
nimbus II:
exellent build, frame is stronger, welds are much cleaner, stronger rim, hub and frame. seat is also much better.
-ISIS cranks, nimbus hub. hub is really strong, cranks are fine for casual riding, can be upgraded for more aggressive riding.
-nimbus gel seat is a pretty good saddle, much better than the lx
-double wall rim, stronger than torker rim
-also has plastic pedals w/ same disadvantages
torker ax:
nice light aluminum frame w/ same components as the lx. only thing you gain over the lx is less weight, and maybe a more attractive frame?? (personal preference)
i would second what skilewis74 said, that you may want to consider a 26". if you have the opportunity to ride one, definitely check it out! it may feel awkward at first, harder to maneuver, but it is a little faster, rolls over bumps better, and is more stable at speed (some may disagree), and it will always be easy to find tires and tubes.