The first thing many native English speakers learn is that the English language itself has many words derived from Latin-based and romance languages. There are six romance languages, French, Italian, Spanish, Portuguese, and Romanian.
Here are 3 I find the easiest as a native English speaker:
Romanian may be the best starter language if you want to learn the six romance languages. Conquer 7-9 of the hardest letters and sounds of the alphabet, and if you can read English, you can pretty much read Romanian in just a few months. (ask my friend who I taught how to read a whole paragraph in 20mins 😉).
Spanish is one of the 2nd and 3rd largest languages spoken in North America and Europe. As it might take a bit of time to understand the structure of sentences and conjugation, once you get the hang of it, you'll see how it may even be easier at times to express yourself in Spanish because there are so many expressive words and phrases.
What are the things that I have personally found to make Spanish one of the easiest languages is the accessibility to learning. You will almost always find a native Spanish speaker with whom you can practice. Versus some of the other romance languages, such as French or Portuguese, you may need to hire someone online to practice.
Similar to Spanish and Romanian, Italian is also a language where what you see is primarily how you say and pronounce words and phrases. Not to mention, sentence structures are one of the easiest to learn as it's similar to English.