There are two types of protection. "Safe Chemistry" and "PCB Protected".
When you say "protected" that typically means that you're talking about pcb protection. These batteries usually have a lithium cobalt chemistry, very high energy densities (3,000 mah and up) and low "c Ratings" (the number of amps you can safely draw in relation to its total capacity).
They make great flashlight batteries but the pcb protection circuit makes them less than ideal for use in regulated mods.
The "safe chemistry" batteries, also known as "IMR" and/or "high drain" batteries, have a lithium manganese chemistry. These batteries have lower energy densities (2/3rds of their equivalent li-co counterparts) but tend to have very high C ratings. Basically they are designed to be able safely deliver high amps. Because of their chemistry, they have no need for pcb protection.
Because of their ability to deliver high amp current and do it safely, they have become favored in the e-cig community.
There are 3 "premium" brands that I'm aware of... AW IMR, Panasonic CGR18650CH and the MNKE.
I own both the AWs and Panasonics and both are very good. I don't own any MNKEs but lots of folks around here swear by them.
The Panasonics are flat tops and I'm thinking that the MNKEs are too... So that would leave the AWs that have the nipple top.
FYI... The batteries carried by Provape are the AWS. It's the only brand they carry and the only one they endorse.
Hope this helps...