Starting with 4x4s – I can vouch for pre-'91 Troopers. Very robust, if a little dated by modern standards. Buy a 2.8TD "Bighorn" Japanese-spec model (like mine) and and you'll at least get electric windows, central locking and maybe even air-con. I'm wary of the later 3.1 engined versions.
Toyota Landcruisers are rightly regarded as one of the best cars in the world. Again, for £1000 you'll be looking at an old one.
Don't be tempted to buy a Range Rover for that kind of money. Or indeed a Land Rover. The Japanese options are much more reliable.
As for cars, that's easy. Mercedes or Volvo. Again, old is best. Mercedes W124s are one of the best cars ever made. Volvo 740 and 940s are also extremely good. The 2.3 engine is the one to have in both cases, though the 2-litres are solid enough.
Most VW and Audis and most Japanese cars are also pretty good. Parts can be tricky for some Japanese models though.
www.gsfcarparts.com and www.eurocarparts.com can help with parts for most German and Swedish cars. Thanks to them, I've found Mercedes to be the cheapest to maintain cars I've had!
Answer:
At that price there is no was any specific model will be more or less reliable than anything else. Buy the best car you can find, check it out thoroughly and if necessary take someone who knows about cars with you.
Doesn't make the slightest bit of difference at that money whether it's a Skoda or a Merc, if it's in good nick, buy it.

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After Top Gear's Bolivian trip they came up with a nearly scrap Range Rover as "best buy"