Difficult one. Yes I think the wooden ones would perhaps be too young for him now. My ds has lost interest in his wooden train set. The Hornby ones though are more for children 10+ in my opinion. Well that was the age roughly when my brother got a Hornby set when we were growing up. He ended up breaking the wheel on the loco though. They are expensive.
My eldest was train-obsessed as a 5 year old and loved Brio. The thing with Brio and similar is that you can get so many accessories and you can play quite hard with them and they don't break. My DS loved configuring different tracks and we had lots of things like bridges, watertowers, a turntable and engine shed. He had a basic Hornby as well, but it required an adult to set it up for him and constant reminders to be gentle with the controls. Also, all it does it go round and round and you can't make it crash or anything or have something happen to the train!
DS1 played with his Brio for years, until about 8. Got it for him at 4. Brio is totally fantastic IF your DS really, really loves trains. My younger two haven't been as keen but still take it out from time to time. DS1 is nearly 16 and still gets excited setting it up for his siblings!
If you're ever in London, the Transport Museum in Covent Garden is fantastic for little train enthusiasts.
My almost 9 year old still plays with Brio. We have just set up out Brio Polar Express set for Christmas. The 15 year old DS2 can also be spotted playing with it too..... ("oh I'm just helping DS3 sort it out")
My 5 yo ds still adores his wooden train set. He has bigjigs which has been great. We've added to it over the years with lots of the accessories. This years addition will be a Brio remote control engine-he's going to be beside himself!
My 5 year old still loves his brio/wooden tracks. And 10 year old dd2 plays with it too.
Mind you, both of hem are still also happy to build things using duplo as well as Lego (sometimes bigger bricks means better stability, or just faster to build!). And both are equally happy to use toot toot vehicles as well as hot wheels if playing with cars.
I don’t get this ‘too old for’ wrt something like a trainset - yes, if your dc was 15, maybe you’d have a point, but surely there’s years of imaginative play left at 5?
Brio all the way! A good expansion pack with bridges and tunnels goes a long way, and yy to the battery operated trains; we have a couple, one of which can pull an extraordinary number of trucks! The other struggles with more than 4 on a steep hill though, bless it.