So, what guitar pick is right for you? Generally you will use a thicker Guitar Pick for a heavier/rougher tone. Lighter Guitar Picks are generally for a cleaner/lighter sound. Personally I prefer the heavier picks.
I have found out that a thick, 1.5m-2mm, Guitar Pick is easier to use once you are familiar with your own guitar. At first a 1.5m-2mm Guitar Pick is hard to use because you stumble and can't push the Pick through the strings, therefore you will find a 0.73 or lighter pick easier to use. But in the long run the 2mm, which I use, allows you to get a fuller sound when shreeding and makes sweeping a whole lot easier. You can always pull the Guitar Pick back a bit to strum multiple strings easier (like brushing the strings).
Thinner, 0.73mm, Guitar Picks are great too. I find that they are easier to use on acoustic guitars. You want to be able to get a degree of volume out of your Acoustic Guitar, therefore a lighter Pick is more durable because of its flexibility. It allows you to brush the strings easier and doesn't get caught when picking strings individually.
You should always choose to buy a Guitar Pick that has a ruffled surface because, unlike the smooth surfaces ones that slip out of your hand when your sweating, the Guitar Picks that have a rough texture to them will allow for a better grip, once comfortably held.
(These Guitar Picks all have rough surfaces and are easy to use)