There is no such thing as 'better' in ecigs - everyone's taste is different. One person will like a 901 and dislike the 801, and vice-versa.
You need to try them. Are you talking about the standard models, or using the atty & cart on something else - which is yet another question, as the result will be different again?
I'd start by reading
through Don's guide to the basics in the Wonderful World of
vaping, in the ECF Library section. Can't do much better than that.
In the end you have to
buy one and try it out, nobody else's opinion is worth anything when you come down to it - only yours counts. There are hundreds of thousands of users of every possible base model and combination, who have tried other variants and would not swap.
It's all in the lungs of the beholder. Or something. Part of the fun is the journey, by the way. It's not necessarily the best thing to get a shortcut, you'd miss out on the journey then.