Hi, If you want a forklift for occasional use on smooth surfaces, buy a used toyota electric. They are cheap enough, bulletproof and practical. Sorry, you may have got good use from your clark, but they are generally a poor machine with flimsy build and mechanics hate fixing them - you can buy them for buttons over here, because nobody wants them. Jungheinrich also make a good electric, but parts are seriously dear. When you buy any electric, the battery condition is the deal breaker, a replacement will run from 2500-7000 bucks, so not to be overlooked lightly.
Propane powered can be troublesome, require a lot of tuning to keep in good running order, and are a pain as they get older. If you were only using it occasionaly a gas engine would be better and less complicated.(Propane ones are just a standard gas engine with a conversion kit on the induction side)
Diesel is the holy grail, but you will pay for the privelege.
Would a skid-steer with a set of forks suffice for your lifting needs? If it would, you can do a lot more with the one machine than just shifting pallets, they are damn versatile little beast - JCB's robot is also a good dual purpose, a mini-teleporter cum skid steer that will lift good weight.
The daddy is the telescopic though, had one, sold it, and now miss it like hell whenever somthing awkward needs hefting - never seen one plough snow before though, but looks ideal for the job. J