This isn’t an easy question to answer. There are pros and cons to both.
What kind of car you would be swapping to buy a 4 x 4? If you are going from a small, efficient car to a big gas guzzling 4 x 4, it’s going to cost more money on all your daily journeys. It depends on how far you drive.
We recently looked into buying an older 4x4 to pull a fairly new trailer. We didn’t want to swap one of our daily cars because they are both small and don’t cost much to run, so we looked into buying an old defender as a 3rd car to pull a newish horsebox.
Even for £5,000, we couldn’t find much in the way of a good defender. Anything that we did find was very old and not too much of a risk. On top of that, we would have had to find a trailer.
We opted for a 3.5 tonne horsebox which cost just under £5,000. I LOVE it so much!!! Driving a horsebox is much better and safer than pulling a trailer, plus I have a lovely little living area to keep all my stuff and chill out in. Yes, you have to MOT and tax it etc. but you also need to maintain a trailer.
There is no right and wrong answer, you need to think about what is right for you.