The ZX5 will take almost any motor you can throw at it. The stock RTR radio system may not be able to handle a hot modified motor. If price is a concern, and your not looking to upgrade (immediately), go for the RTR. There are a few wheels out there for them, and many different tires. If your REALLY adventuresome, I am sure you could do a truck size wheel conversion and gain quite a bit of ground clearance for bashing around.
Batteries have changed drastically since you were in it last time. Lipo is becoming more and more popular, light weight, tons of run time. They do require a specific charger, and are a bit more costly than standard NiCd or NiMh batteries though. Without a low voltage cut off (can be purchased for around $25), Lipos can be discharged to low (like running your car until it slows WAY down) and swell or explode.
I race a ZX5 and love it. I use Lipos and a Novak GTB brushless system. I have more power than I need on any track I drive, and runtime is NOT an issue. I can run around 10 minutes on a 3200 Orion Lipo.
If your only going to run around the backyard/parks/up and down the street, a stadium truck will probably be better, unless you just love the buggy style/look.
In the end, get what makes you happy. If you dont, you will end up buying again and again until you get what you want.
--Joey --Venom Batteries & Chargers!!
Old School Racer & Vintage RC Car nut
RC10CE (X4),B2,B3,B4,B5, B5m, B6D - 10T,T2,T3,T4,T5M - B44.3
BRZ-444, RC10M, RC10L3 oval, L4 oval X 2