The only problem with the ones that look like regular cigarettes is that the batteries don't last very long, so you have to make sure you have several so you can be charging one while using another. And the batteries are generally good for a certain number of charging cycles. So a smaller battery means you are charging it more often and it doesn't last as long before needing to be replaced.
Besides the battery, the next choice is whether to use a cartomizer or a clearomizer (tank looking thing).
The advantage of a clearomizer is that you can see how much liquid is in it so you can keep it filled without overfilling or letting it run dry. They also tend to last longer than cartomizers.
But I've tried a few different clearomizers and haven't liked them that much because the vapor isn't warm, so you can't feel it as much.
As far as liquid, you just need to try a number of different flavors to see what you like. I've had some that I thought were horrible and some that I love. I can't stand any of the tobacco flavors I've tried and I don't like anything with citrus (all tastes soapy to me). So I stick to bakery and fruit flavors.
My current setup is:
X2 batteries from Smokeless Image
Blank cartomizers from Smokeless Image
E-Liquid from Heather's Heavenly Vapes in a 70/30 VG/PG ratio (Cinful Pear and Just Peachy are my favorites). I also like Caramel Cappucino, but the coffee flavors tend to clog up the cartomizers much faster than other flavors.
I also like Cheesecake and Irish Mintz from Mad Vapes.
And I like Watermelon and RY4 from Smokeless Image. RY4 is supposedly a tobacco flavor, but it tastes more like caramel and vanilla.
Rawr Vapor has a lot of good flavors, but they tend to be too sweet, so I can't use them very long without getting sick of them.
If you don't want to spend too much and just have him try it, I'd suggest the basic starter kit from Smokeless Image, plus one extra battery, and choose one of the sample packs for the cartomizers, so he can try a few different flavors. Personally, I would pick the Strong or Sweet sample pack, but some people like the tobacco flavors.