From creating memes, book trailers and covers, Book Brush offers it all in one easy spot. I use them all the time and they simply keep getting better. Use SARTOR15 to get a lifetime 15% off a paid subscription.
A suite of tools that I find I use all the time is housed in Adobe’s Creative Cloud. You can subscribe to various elements of the suite or all of it. Often they will give you a starter deal, so ask. *
Canva is a free or subscription design tool filled with templates to help you design quickly and graphics to help you design.
PicMonkey is a paid subscription but offers a free trial for creating memes for social media, artwork for blogs and websites. You name it.