If you are looking for a no problem E-Cig with easy refills, Great Vapor, Perfect for driving or going out...my choice would be the KR808-D1.
They work great, look great. Not too expensive if you use the condom method and refill the Carts.
If you want to go "Big Battery Mod" the Silver Bullet is a good choice. It has no button problems, but it is a big hunk of aluminum.
Or you can go the cheap way and try out 5v vaping with a box mod.