Which of these 5 languages is the easiest to learn / speak for a native English speaker? ?

German since a lot of English derives from German. 

The other languages are all very similar. Spanish is probably the easiest since most English speakers get at least some exposure to it everyday. French would be the hardest because the pronunciations are so hard for English speakers. Italian somewhere between those two. Portuguese is similar to Spanish but it can be tricky sometimes. 

I vote for Spanish. I'm a native USA English speaker, and I found it reasonably easy to learn enough Spanish to get by.

According to the US Foreign Service Institute, German takes a little more than Spanish, French, Portuguese or Italian. It lists all romanic languages as "600 hours of class", but german at 750

Esperanto is (or once was) listed as a mere 150 hours, and learning it first doesn't even cost extra time.

see wikipedia Propaedeutic_value_of_esperanto

From personal experience: German was the easiest for me to learn, French was more of a struggle. Portuguese I tried but nothing ever stuck, Spanish & Italian I can speak the basics but don't understand the response...

My guess/opinion based on my own knowledge of all these languages, is French or Spanish would be the easiest. 

So WHO do you expect to be conversing with in the language?  Or maybe just reading??

In my opinion Italian is the easiest.  The hardest part is the prepositions, but you get past that.

German would be the most difficult language out of the choices you have given us.  There is High German and Low German, the umlatts, etc.  French, Spanish, Portuguese, and Italian are Romance languages derived from Latin so word recognition and meaning would be easier.  

For an English speaker, German would likely be easiest as it follows most of the same rules as English. Spanish and Italian would probably be second as they are phonetic. Portuguese and French would likely be the hardest of this group given their written rules. 

Spanish is the easiest.  

it is sort of a tossup between German and French.German has a very difficult grammar but it shares some wordorder snd many words.Spanish,Portuguese and Italian are more difficult
A little Spanish comes easy but to become very good is not.