With VE's, anything Series 1.5 onwards (about 2009ish onwards) is a safer bet, as they came with the more reliable High Feature V6 engines and 6 speed auto transmissions, which are reliable if maintained, however can get expensive if things go wrong...
Pre 2009ish Alloytec engines weren't too bad if maintained, but they were more likely to have timing chain issues, however the transmissions were a different story, with the 5 speed auto being pretty garbage mechanically- The 4 speed auto is good if maintained, however they're pretty ancient and are only found in the more basic VE Omega's and Berlina's pre 2009, which will not have any sort of beep beep noises and still have green LCD screens
Anyways, what you're probably going to want is something VE Series 2, that is an SV6 or Calais, as they came with the 3.6 Litre LTT/LFX motor which has better performance over the 3 litre LF1/LFW (found in the Omega and Berlina), which is certainly adequate, however may struggle a bit more with towing heavy loads due to less torque... In addition, the Series 2 comes with extra technology over the Series 1, and will feel a little more modern, however even the newest of VE's are at least 10 years old, so don't expect technology seen in today's cars...
Something that has been well maintained both cosmetically and mechanically with around 100-200 thousand km should be a solid car for family duties, though don't overpay and avoid abused examples, unless you get them very very cheap... If you can afford the extra fuel, I'd go for the V8 as you get more power and better resale value, though I'd probably be more inclined to go for earlier examples to avoid the AFM dramas on the later VE's...
One last thing to note, consider your options by looking at other makes and models, and don't rush to buy a car, as you're more likely to be ripped off... Also, do a PPSR report on examples you're very interested in, make sure the car is cold when inspecting, and if buying from a dealer, read the fine print on warranties as many of them aren't even worth the paper they're written on...
Happy car shopping
