Should I upgrade to a newer lens or newer camera or both?

Hello, I have been reading posts in many of the forums here for years and have learned a lot. Thank you everyone! I have finally decided to join and post a question.

I have enjoyed photography most of my life, but still have so much to learn. After taking a couple of formal photography classes about 10 years ago, I purchased my first DSLR camera - a Canon T2i. I chose a Rebel camera because of the size and weight. I also have stayed away from any heavy lenses for the same reason.

I recently moved from Hawaii to a mountain town in Colorado after retiring from teaching. I enjoy shooting flowers, nature, landscapes, architecture, and shooting town events such as parades, hot air balloons, etc. I love to hike and travel to Italy. Photography is a big part of both hiking and traveling for me. If I had to pick one theme, I love to shoot things with lines. I am not very much into portraits although street photography is fun now and then.

I own the following lenses: 18-55 IS kit lens, 55-250 IS lens, 60mm F/2.8 macro USM, 10-22mm F/3.5-4.5 USM lens, and recently I purchased the 40mm & 24mm STM pancake lenses.

I feel like I have made some nice strides in my photography and am ready for some sort of upgrade. A year ago, I started thinking about purchasing a newer camera. I really liked the SL1 with the smaller size and weight but then started reading rumors about the SL2 so I waited. Well, we all know that the SL2 never happened.

Last month when I finally gave up on the SL2, I wondered if maybe upgrading to a newer lens might be a better option. I love my two little pancake lenses but there are times when having to keep changing lenses is just not practical. At first, I thought that an easy and cheap solution would be upgrading to the newer STM kit lenses. I started reading a lot about the differences between the IS and the STM kit lenses. I am still not clear though how much better the STM lenses would be. I also read a bit about the 18-135 STM but then started to think about upgrading to an even nicer lens.

After doing tons of research, I became very interested in the Sigma 17-70 F/2.8-4.0 USM C lens. I have read some very nice things about the Sigma 17-70 and it is not as heavy and as expensive as Canon lenses in the same range. As a nice little bonus, it can handle some macro shots, although it is not a true macro lens. I also considered the Sigma 17-50 F/2.8 as it would be even nicer in low light situations but there have been some issues with this lens which if I recall correctly have to do with motor noise. The 17-70 would also give me a little longer range. In the past, I would have never considered a Sigma lens but have recently read quite a few nice reviews on some of their newer lenses as well as have seen some nice youtube reviews.

Yesterday, I came across a thread talking about the Canon 6Ti camera and the improved autofocus system with 19 points, all cross-type. I never really considered that camera before even when it first came out since it would be adding a bit of size and weight from my 2Ti camera, but in the end, what I want most out of my photography are the best shots I can get and the upgraded focus system might be what I want more than a smaller size camera.

What to do? As you can see, my thoughts are all over the place. I finally joined to start this thread to hopefully get some opinions from others.

What would you do?

-Go for a better lens at this point and wait on a camera since my T2i is not that terribly old and is still in great condition? Maybe just one day, there will be an SL2 that will come out with a better autofocusing system. Any thoughts on the Sigma 17-70? Other advice on a lens?

-Go for the SL1 since it is such a deal right now along with a new lens?

-OR wait on the lens and go for the even better T6i camera and just deal with the bigger size/heavier weight? I know it is not significantly bigger/heavier but it is definitely going in the opposite direction from the SL1 size. Right now, it looks like I can get this camera for the same price either purchasing just the camera body or the camera and the 18-55 STM lens.

-I am also wondering if I should pick up the new 50mm F/1.8 STM lens? I already have a 40mm and a 60mm although I don't have any lenses that are F/1.8 lenses. It's a pretty cheap lens.

-And any thoughts on the newer 55-250 STM lens? I have read that this lens is a little better than the early IS version, although enough for an upgrade?

Thank you in advance for taking the time to read this post and for all of your kind advice. I look forward to hearing your thoughts.