I just used plain water in a lidded cup along with meals when ds started on solids. There is no need for any juice although if you did choose to give it then ordinary fresh fruit juice well diluted with water would be just as good as so called 'baby' juice and is much cheaper too.
Lots of people will suggest juice but I'd hold out as long as you can. My ds eats a lot of fruit anyway. His CM gives him juice (I haven't been able to dissuade her) but he's cool with just having water and milk at home still.
If at any point you do end up giving juice, don't give it in a baby bottle, a cup with a spout's not so bad but the bottle teat directs it straight on to any teeth he has, and that's a reason why it's a good idea to steer clear of juice while you can. When/if he does start having sugary drinks a straw directs them away from the teeth at least.