mix of both, but preferably a young squad you can keep them longer
i normally have middle aged players but if i'm a low club i get the better free players (which are usually old)
i personally go for youth. my squad age on average is 24
With my Boreham Wood team its both, with no middle aged players!

Ideally I'd have young players but the best free players are normally 30+
I buy young players for the future, but they'll all get old, but yeah- youth.
I like old. Talent available on the cheap.
youth... usually 1st season my Avg age is 19-20... I really don't mind losing cups and championships because in 2-3 years I get on and start taking with my built-up team.
A combination of the two.

I tend to lean towards youth players (under-24s, anyway) but I try and ensure I have at least 2 players who can offer experience and hopefully captain the side.
I prefer youth because their atributes are goin' up,while a old players atributes are lowering.'Nuff said
Both. I like developing youth into the team, but you can get some great oldies who can still do a fantastic job.
i can never get the youths to live up to their potential so i just buy new middle aged players