Looking at the options that you have suggested I think the best car for you would be the 99 City as it meets all your needs, i.e. reliability and maintenance facilitation, good on highways etc. The reasons for disqualifying the remaining models are as follows on the basis of my point of view and what I have heard from friends, in the end the final decision is yours:
1-Mini Pajero 98 model above
Expensive parts, not widely available, maintenance parts are also on the higher side, often abused, engines do not have an exceptional longevity and these factors are all contributors towards their low resale value. The engines do need a lot of care and timley maintenance, I have heard very frequently of blown turboes and expensive replacement, a bit underpowered for the motorway and blocky shape makes it sway in cross winds
Great reviews, good engine, maintenance parts etc are available albeit a bit on the expensive side as are all mitsubishi parts, body parts are few and far apart thus expensive (head and tail lights, indicator, front grill etc), if you can afford the maintenance then a pretty good all rounder
3-Gemni Sierra (over Potohar frame)
Horrible suspension unless its the coil sprung model, avoid the leaf sprung model at any cost, at the slightest dip or bump on the road the car will become airborne, if you're going for a genuine Jimny Sierra they're not too bad but top speed is not that great and accelleration is cumbersome, which makes them very dull on the motorway
4- Alto 2007-8 model
Quite thirsty on the motorway with the AC on at high revs, you already have a Cuore which is a better driving vehicle in this category, I wouldnt get 2 cars in the same category, also comes with a host of annoying rattles and squeaks in due course, I hated mine but a lot of people love theirs...
Aparently delicate electrical components, plenty of problems in older models, sensors clog up and the car acts all funny, I have never owned one myself though so this is just what a friend said about his although he really used to drive like a saint and took a lot of care of his santro but started having a lot of electrical issues after 25k km, and last but not least they're all butt ugly...
6-Chevrolet Joy/Ex 2005-2006
Dont know anyone who's owned one so cant say
7- City 99
Great car, very comfy, great pick, good economy, the first generation Honda City established the City market in Pak, has all the basics electrics and power steering etc, good respectable looking family saloon, still very well regarded despite its age thus plenty of buyers, spares and maintenance parts are reasonably priced, more expensive than Suzuki but cheaper than Mitsu and widely available