Name changed as I appreciate this is going to come across as complaining my diamond slippers are too tight, but here goes... (I realise I am in a very fortunate position!)
My DP and I are ftbs, currently looking to buy. We've spent our twenties and early thirties moving frequently for work, and have never been able to settle anywhere until now. So we have been able to save a healthy deposit.
Where we are currently looking, there is a shortage of four bed houses, so there is a large gap in price (typically 50-75k). We can afford to buy at the lower end of the four bed house range, but you're obviously getting something that needs some work. Alternatively, we can buy a three bed of "better quality" and save a lot of money. We do not currently need four bedrooms (no kids yet, and no short term plans for them), but we have been drawn to four beds because they tend to have larger rooms downstairs. Our current rental feels a bit pokey, so space has become a bit of a thing.
When I say "afford" I am talking about mortgage payments being the same as our current rent. A three bed is tempting as we do not need a huge house and paying less each month would obviously be lovely (although not particularly necessary).
However, I have always been told you should stretch yourself for your first house to put yourself in the best position for the future, but is that really true? Would you buy a house bigger than you need because you can?
Regardless of the house we go for, it is unlikely to be a forever house.