Both sites are good and it really depends on on people preference on which site he would use but as a newbie I would go for bittrex. Knowing poloniex does experiencing problems as of now.If you don't like any hassle then go for bittrex but it still depends on you if you find out that poloniex suits for you then better choose on which you are comfortable with.
What do you think so that you can choose bittrex as a place for newbie?
Whether the problems that exist in Poloniex could cause the newbie confusion?
I think it may not be like that, it may just be your speculation that states it, but I think the newbie would understand the simple problem that existed in Poloniex.