If you're lucky enough to have friends that will come for a ride, the 156 would be a better choice - far less embarrassing than if you have to make people climb over a seat to get in the back (there seems to be a stigma attached to sitting in the back; an unvoiced argument seems to happen between your guests...)
On a slightly-related note...
In 2006 I decided to buy an expensive modern car ("stop wasting money on old cars", they all said...) With my generous budget of $25,000 (£9900 - a year's income), I could afford either of two choices - a three-year-old FIAT Stilo Abarth, or a five-year-old Alfa Romeo 147. I settled on the Stilo because I preferred the styling (!) and it came with more electronics, such as reversing sensors and voice control (!!)
After just over a year, I realised that the actual driving experience wasn't nearly as nice as my old Alfa 164, and it really was just a large hatchback loaded up with goodies and a wonderfully powerful engine, but still only a hatchback (with a twist-beam rear axle), so I sold the Stilo ($16500) and bought another 164 ($1000).
I still have that 164 and I just can't believe what a value-for-money contrast there is between the Stilo and the 164. I don't think I'll ever buy a three-year-old car again. Not when you can buy a whole fleet of great cars for less than one-quarter the price... and you get so much more engineering for your money.
I then bought a Punto ($5000), which to be fair actually drove worse than the Stilo... and again it was very difficult to get anyone to sit in the back. And it's also hard to be bothered putting bags, boxes etc. on the back seat, since it means fitting them through the gap between front seat and door frame.
If you have a three-door car, it's "too small" for more than two people (regardless of whether it's the same length as the five-door version, which it usually is). Although it isn't any smaller, people think it is. And because your front doors are longer, you can't open them as far in carparks etc. A small but noticeable point
Now after ending up with a 156 ($5000), I realise the same-platformed 147 would have eclipsed the Stilo in terms of driving experience, not that that's the point of this thread... it's just that I bought the Stilo because I thought the 147 looked too, err, 'girly'.
The 156 is a nice medium size, smaller than my 164 and larger than my Punto, and people will actually sit in the back (at least, they will after they realise it has rear doors!
If you intend to use the car everyday, I think practicality ought to count for something - and a 156 GTA with a tow bar would surely be a practical vehicle...