Hi and welcome
Do you have a good standard rescue within your reach you can adopt an already bonded pair or trio from?
Any of these combinations works with the right personality match - and herein lies the crux: it is less important what you ultimately opt for but whether the piggies gel. Let the rescue choose your piggies for you; they know what to look out for, so you'll get the greatest enjoyment out of your piggies. A happy bond and balanced personalities are so much more important than gender, age or looks. A good rescue will also be prepared to bond a trio for you, so you can bring them home without worries of a husboar not being accepted by the sows. Sow trios are generally fairly rare in rescue; boars are more common.
You have to get used to some smell whatever the combination. Younger boars are generally smellier, but they are also generally more vocal (but that is very personality dependent) and more playful than girls, so you'll never get it all. Each gender has their great points and their own problems.
When you opt for a mixed gender trio, you have to be sure that the sows are good friends; otherwise you'll end up with an outsider problem as the boar will side with one of the sows in the longer term. The same goes for a sow trio.
Sows: Behaviour and female health problems (including ovarian cysts)
A Comprehensive Guide to Guinea Pig Boars
The rescues in our links have all been carefully vetted to make sure that any members and guinea pigs are in safe hands at all stages of the process and that welfare recommendations, good practice and ethics are observed. You will adopt only fuly quarantined, properly sexed and carefully matched piggies that are fully healthy at the time of the adoption and do not come with any nasty surprises. That is a lot more service than you'll get anywhere else.
Recommended UK rescues:
Recommended Guinea Pig Rescues
Recommended rescues in several other countries:
Guinea Lynx :: Rescue Organizations