I've attached the logo I'm currently using. I don't hate this logo, but it's something I made myself, and I'm a developer, not a designer. So, it's poorly executed.
In general, I like the concept of the current logo, but it doesn't work practically very well. I would like a logo that can be printed in B&W, which this one can't do because it's got a gradient to the colors and no outline. That's also a problem when I want to print it on t-shirts, since you have to pay per color. Ideally, my new logo could easily accommodate printing in B&W and in color on t-shirts without having too many different colors. (at least a variant of the logo with fewer colors)
All that said, I'm not totally wedded to the concept of my current design. Ideally, I'd get some concepts that were better versions of what I have and some designs that were totally different.
The Drupal CMS logo is a drop, so if you look at development shops and training sites that work with Drupal, they tend to incorporate drops in their logo. It's not 100% critical, but it some water theme would definitely tie the logo to Drupal project. Some examples from training competitors:
Examples from Drupal development agencies can be seen here: https://www.drupal.org/drupal-services
The agency logos often don't have a drop connection because these agencies work in more than just Drupal. DrupalTutor.com is exclusively Drupal, though, so I think it would be more important to have some connection. If you scroll through a few pages the agency list above, though, you will see some good examples of how people have used the drop without being too literal. The Wunder Group logo is a great example of that: https://www.drupal.org/wunder-group
I'm open to any color suggestions. Obviously, water is blue, so that's what you see a lot of Drupal-related sites, but I'm definitely not wedded to that color.
You should also ignore any design elements/fonts/colors you find on the current DrupalTutor.com website, because, again it's something I put together 5 years ago and I'm not a designer. I don't particularly like what's there now. My plan to is rebuild the website in the next year, and I will base the design of the website off the new logo and whatever fonts and colors come out of that.