易しい(やさしい)、簡単(かんたん)、優しい(やさしい)...!?
易しい(やさしい) = 簡単(かんたん) = easy, simple
And "易しい(やさしい)" sounds same as "優しい(やさしい)"
But they are different in meaning.

When I want to speaking "easy or simple" in sentences.
Should speaks "簡単(かんたん)" , right?
Ex: 日本語は易しい(やさしい)ですか。→日本語は簡単(かんたん)ですか。
Which one is better in speaking?

易しい(やさしい) = 簡単(かんたん) = easy, simple
而 "易しい(やさしい)" 和 "優しい(やさしい)" 的發音是一樣的。
但是兩者有不同的意思。

當我想要說"easy 或 simple"在句子中。
應該說 "簡単(かんたん)" 對嗎?
例如: 日本語は易しい(やさしい)ですか。→日本語は簡単(かんたん)ですか。
在談話中哪一種比較好?

Question

易しい(やさしい)、簡単(かんたん)、優しい(やさしい)...!?
易しい(やさしい) = 簡単(かんたん) = easy, simple
And "易しい(やさしい)" sounds same as "優しい(やさしい)"
But they are different in meaning.

When I want to speaking "easy or simple" in sentences.
Should speaks "簡単(かんたん)" , right?
Ex: 日本語は 易しい(やさしい)ですか。→日本語は 簡単(かんたん)ですか。
Which one is better in speaking?

易しい(やさしい) = 簡単(かんたん) = easy, simple
而 "易しい(やさしい)" 和 "優しい(やさしい)" 的發音是一樣的。
但是兩者有不同的意思。

當我想要說"easy 或 simple"在句子中。
應該說 "簡単(かんたん)" 對嗎?
例如: 日本語は 易しい(やさしい)ですか。→日本語は 簡単(かんたん)ですか。
在談話中哪一種比較好?

Answer

Almost same idea as former(upper) answer. 

Both 易しい and 簡単 are okay. But people are more likely to use 簡単. 
This is maybe because 易しい is often confused with 優しい, just like you are pointing out. 

And usually 易しい includes the meaning of "for learing" or "for understanding" .. So usually it is not used as the meaning "simple". 

As reference for you.

Answer

Ex: 日本語は 易しい(やさしい)ですか。→日本語は 簡単(かんたん)ですか。
Which one is better in speaking?

→日本語は 簡単(かんたん)ですか。
This one is better.
Both are natural and you can use both but I think people more often use 簡単 than 易しい.

易しい(やさしい) means easy but I think 易しい(やさしい) doesn't mean simple
簡単(かんたん) = easy, simple
優しい(やさしい) means gentle. usually use for people.
EX.　彼は優しい人です。

Answer

I think 簡単(かんたん) is more common.